Mechanics

You have 7 inventory slots now. In exchange, the part of the interface is gone.
Attack, Accuracy, Avoid, etc. can instead be checked in the small window on the map.

Similar to Thracia 776, there are accessories that give bonuses just by being in the unit's inventory. They will be marked in the description as holdable.

These accessories usually have a slight negative effect as well as the positive. The only limit to how many holdable accessories one unit can carry is their inventory space.

Some accessories that give skills, bonus stats, and/or affect growths may instead be equippable. A unit can only have one Equippable accessory at a time, on an exclusive inventory slot.

Instead of being items, monster weapons have their own weapon rank.
+3/-3 Damage given taken, +25 Hit, +10 Avoid for every rank at S rank and above.

This time you don't have to worry about durability. Instead, some weapons have a cooldown system, which makes them unusable for a few turns. Myrrh won't be at risk of losing her Dragonstone.

Magic and some physical weapons have elements associated with them. They can cause statuses and/or deal super effective damage.
The elements are:
Light
Dark
Water
Ice
Fire
Thunder
Wind
Earth
Some weapons have multiple elements.
If a weapon has an element (or more) associated, the description will indicate it.

There are more types of effectiveness in FE8R. We have effectiveness of unit type and effectiveness of status.
Unit type:
Horse
Armor
Flying
Infantry
Sword
Magic
Pirate
Dragon
Monster
Status:
1. Drenched
2. Seared
3. Shadowblight
4. Frozen
5. Rock Punctures.
Of course, this means that elemental weapons can be more dangerous.

Effective damage deals +5 DMG and x3 Damage Multiplier. Very Effective deals +32 DMG and x3 Damage Multiplier.

Using a certain element or Heavy weapon while a unit is inflicted with a certain element will create an elemental combo and deal Effective Damage.

Combos ( after , after , after , Heavy after )

Functioning similarly to Fire Emblem Engage, heavy weapons always attack second and can't double the enemy by regular means. Here they're also effective against frozen enemies.
These weapons will shove the attacked unit.

Additionally, in particular: Blade attacks will Cleave when initiating.
Greatlances gain +2 Range on Enemy Phase.
And Warhammer attacks inflict Flinch on enemies within 2 tiles of target.

In this game, there are two kinds of staves:

Support staves can only be used by support classes. Support classes have a staff icon in their description.

Offensive staves can be used to attack and don't have the support class restriction. Some of these staves will always hit, giving staff users a safer attack option, but they can't crit.

Bows have better range than in the original. Most bows now have 2-3 range. Bows are also effective against Anima, Light, and Dark magic, on addition to Flying enemies.

Some weapons use stats that aren't just Strength and Defense (for physical weapons) or Magic and Resistance (for magical weapons).
If a weapon has one of these different damage formulas, it will be noted on the description, if two or more stats are used to calculate Attack, the value will be shown as well (before adding Might).

Some weapons have special properties besides the typical ones for their type. These properties include skills, combat arts, status effects, stats improvement and even water walking.

Some items (primarily character Arsenals) that contain more than one weapon. These weapons can't be stolen.

Slim weapons of every kind can be found in the ch2 shop and grant extra WEXP.

Fire weapons (of any kind) are effective against Horse units.

Thunder weapons (of any kind) are effective against Armor units.

Wind weapons (of any kind) are effective against Flying units.

Light magic is usually 3 range.
Light magic and daggers will do extra damage when doing a critical hit. This means that even if a normal hit would do 0 damage, you'll damage the enemy with a critical hit.

From chapter 5 onwards, bosses will have an ability that revives them a set amount of times (like in Fire Emblem Engage).

They will also, typically, wield weapons that can counter attack at any range and cannot be stolen.

Starting in chapter 3, there will be minibosses that drop weapons. They may also have Revival Stones.

The weapon triangle's effects can be higher than in the original games.

They can affect your critical hit rate against enemies.

Bows are part of the weapon triangle and have an advantage against magic.

Swords and Light vs Axe and Dark: +4 DMG, -2 DMG taken, +10 Hit, +20 Avoid, +5 Crit, +5 Dodge.

Axe and Dark vs Lances and Anima: + 6 DMG, -2 DMG taken, +20 Hit, +20 Avoid, +3 AS.

Lances and Anima vs Swords and Light: +2 DMG, -4 DMG taken, +5 Hit, +10 Avoid, +20 Dodge.

Bows vs All Tomes/Staves: +15 DMG, -10 DMG taken, +30 Hit, +10 Avoid, +8 Crit.

Some unit's may be able to summon weather effects such as sandstorms through certain weapon skills. They stack with each other freely, and only affect enemies.

Growth rates are now visible in your unit's info. Your units' growths can change in several ways:

Promoting: Now, besides gaining stats, your units get bonus growths upon promoting, sometimes drastically altering the unit's statline.
Conversations: some base convos can improve an unit's growths.
Held items: items that used to be stats boosters or promotion items are now held items that among their effects, typically improve a unit's growth rates. Metis Tome's effects have been improved.

All of your units have Con and Mov growths, so they have a chance to level up those stats.

This game features Pair Up and Dual Strikes as they function in Fates, only without stat bonuses for pairing up supported units.
The higher tier a unit is, the higher the bonus that unit gives when paired up will be. The total bonus depends on the unit's current and past classes.
This means that two characters with a different base class will retain that differing pair up even if they promote into the same class.
The type of Pair Up bonuses are the following (if two bonuses are listed together it's because they count as the same):
Lord/Manakete
Knight
Cavalier
Pegasus
Priest/Cleric
Fighter
Pirate
Archer/Thief
Monk/Dancer
Mage
Myrmidon
Mercenary
Wyvern
Shaman
Priest/Cleric Pair Up makes lead unit inmune to negative status and heals a bit of health at the start of the turn.

While paired up, the Guard Gauge increases by 2 every time your unit attacks or is attacked (missing counts for this).
When the meter reaches 10, the next attack from the enemy will be blocked.

When two units are Paired Up, they can use a combat art named Affinity Strike.
If the unit kills the enemy, it gains Galeforce, but stats are reduced by 90% for a turn.
Additionally, they inflict a status that depends on the Pair Up partner's affinity.
Enemies can be paired up too. Though they cannot Affinity Strike, and instead gain a 50% damage increase.
Affinity Strike's status effects are, by affinity:

1. -> Seared
2. -> Breached(8)
3. -> Stunned
4. -> Cursed/Shadowblight
5. -> Reduced Vision
6. -> Frozen

7. -> (has a 50% chance of inflicting each of Seared, Drenched, Cursed/Shadowblight, Frozen and Rock Punctures)

Bonus Experience (BEXP) is a mechanic that allows you to give experience to your units outside of battle with the cost increasing with your unit's level and tier.
Certain actions like visiting villages or houses (even those that give you no items) can give you more BEXP.
Clearing a map before a turn limit will give you more BEXP. Clearing a level of the Tower of Valni or the Lagdou Ruins also gives BEXP.

In Hard and Lunatic mode, there are options of 1RN and 2RN. They correspond to the type of RN (Random Number) system used in hit rate.
1RN: Used in FE1-5. No modifications. A 70% displayed chance to hit is exactly a 70% real chance to hit.
2RN: Used in FE6-13. The engine generates two random numbers and averages them.
This makes displayed chances to hit above 50% more likely than expected, and those lower than 50% less likely than expected. A 70% displayed chance to hit is actually 82.3%.

When you start a new game, you'll be asked to choose a growth method.
Random: Truly random growths. For each stat, a random number is rolled between 0 and 99. If the number is less than the growth rate, that stat increases.
Fixed: Units will always have their average stats. A unit with a 50% growth rate is guaranteed to get a stat increase every other level.
Dynamic: Like Random, but it applies a rubberbanding effect to the growth rate. If a unit fails to increase a stat on level-up, next level-up that stat will have a higher effective growth rate.
All methods result in the unit having the same average stat as they level up.
For instance, a level 1 unit that starts with a Speed stat of 5 and a speed growth of 40, under all three methods, will end up with, on average, a Speed stat of 13 at level 20.
The only difference is how wide the variance on the results will be, with the Fixed method having no variance, and the Dynamic method having reduced variance compared to the Random method.

Both Eirika and Ephraim will have access to the convoy regardless of which route you chose.
Eirika and Ephraim's classes have higher stat caps than other classes from the same tier.
The Lord of the route you didn't choose will return as a Tier 3 unit in chapter 15.

Your trainees and Myrrh have the Paragon skill (makes the unit gain double Experience) when they join. They will lose it upon promoting.

Your classic trainees have a special ability that increases their crit chance by their internal level.
Your trainees also have three T1 promotions.
Ross can promote to Fighter, Pirate or Barbarian.
Amelia can promote to Knight, Soldier or Wyvern Rider.
Ewan can promote to Mage, Shaman or Monk.

You have the option to have Franz, Neimi and Natasha join as a trainees instead of their usual classes. They'll have some special promotions if they start as a trainee.
Their T1 classes options are:
Franz: Sword Cavalier, Knight and Mercenary.
Neimi: Archer, Outlaw and Kyudoka.
Natasha: Cleric, Troubadour and Medic.

With the exceptions of Amelia, Ewan and Myrrh, units now come at a more reasonable level making easier to use them.
Some will promote when you get them or before the map starts. Beginning with chapter 10, units will begin at T2. At chapter 14, they'll be T3.

Like in FE6 and FE7, units that start as enemies are stronger in Hard, Lunatic and Aria mode.

Each unit has an arsenal with their Prf weapons. Your units will unlock and in some cases replace their weapons when they get enough Weapon Experience.
Some units will replace their Prf weapons after an event.
Some units have new dialog in their joining chapter that indicates their proficiencies, in red text, so you can notice it more easily.
Your units' arsenals' description includes icons with their proficiencies, which gives a hint of what they can use on some promotions.
Keep in mind that some units can't promote to classes that let them use the full arsenal.
Just because two units' arsenals have the same weapon types it doesn't mean that they'll play the same. Their Prf weapons can have different effects/properties.

Seth starts weaker than in the official games. Luckily, he can regain his strength on two ocassions:
His C support with Eirika.
A base conversation in chapter 9 (this conversation requires you to keep a certain healer alive).
Both of these events will give Seth stats and increase his growths.

Orson's items are exclusive to him and cannot be traded.

There are many more units available to the player than in vanilla FE8, inlcuding community made units, found in the Dragon's Gate.

You can get your own monsters. They're optional and you can obtain them after beating certain maps, with the exception of one pair which joins in a base conversation. They have their own arsenal.
If Lute and/or Knoll are alive, they can revive your fallen monsters after falling in combat even in classic mode.
Your Gorgon starts as a T2 and she counts as being a promoted Shaman. Your Cyclops also starts as a T2 and is considered a promoted Fighter.
Monsters only get promotion choices for T3 classes.
There's a new Monster line: the Tarvadour, a support class that is a horse type.

You have the option of creating your Avatar. After chapter 1, a new location will appear in the world map.
When creating the optional MyUnit, you'll have to choose a Boon (strong point), Bane (weak point) and a starting class (only excludes Lord classes) that includes monster classes.
At levels 5 and 15 of each tier, MyUnit will gain another skill from a list of 10 skills that belong to a class from the same tier.

Unlike the original game, certain actions won't end your turn. Support conversations, Talk and using consumable healing items are free actions.

Supports are now easier to obtain, and more similar to how it works in Awakening.
The limit of supports is that you can only have one A support. You can have all the B supports you want.
If you obtained enough points in the previous map to trigger a conversation you can activate it from the base too.
The range for getting support points is now is 2 spaces
There are more ways to gain support points besides ending turn near each other:
By interacting (using staves or dancing).
By battling on range of the partner.
By battling on pair up with a partner.
Support bonuses have been buffed to compensate the increased enemy power.

Fire (C/B/A): +3/6/12 DMG, +5/10/20 Hit, +5/10/20 Avoid, +2/4/6 Crit, +3/6/12 Defense Speed.

Wind (C/B/A): +3/6/12 DMG, +5/10/20 Hit, +2/4/6 Crit, +5/10/20 Dodge, +3/6/12 Attack Speed.

Thunder (C/B/A): -3/6/12 DMG taken, +5/10/20 Avoid, +2/4/6 Crit, +5/10/20 Dodge, +3/6/12 Attack Speed.

Ice (C/B/A): -3/6/12 DMG taken, +5/10/20 Hit, +5/10/20 Avoid, +5/10/20 Dodge, +3/6/12 Defense Speed.

Dark (C/B/A): +3/6/12 DMG, +5/10/20 Hit, +5/10/20 Avoid, +2/4/6 Crit, +5/10/20 Dodge.

Light (C/B/A): +3/6/12 DMG, -3/6/12 DMG taken, +5/10/20 Hit, +5/10/20 Avoid, +2/4/6 Crit.

Anima (C/B/A): +3/6/12 DMG, -3/6/12 DMG taken, +5/10/20 Hit, +5/10/20 Avoid, +5/10/20 Dodge.

Your units can go up to Tier 3, like in FE10. T3 classes have a level cap of 30.

When you're in the promotion screen, you can see the weapons that each class uses and the skills it learns.
Both the Dancer and Manakete classes are T2 classes, which means that they only promote once.
T1 and T2 units promote automatically after their level cap, but they can promote earlier if you use a Master Seal at level 15 or later.
The Master Seal won't be consumed after being used.
In general, promotions are made so that you don't discard weapons, but there are some exceptions.

All classes learn skills by leveling up. Skills are learned at levels 5 and 15.
Some classes have level 1 skills like Canto or Steal.

Stealing and opening locks is a bit different here.
You don't need lockpicks to open chests/doors.
You can steal enemy's unequipped weapons.
There are certain weapons that you can't steal to prevent cheesing certain enemies.
You can steal with a full inventory and they will ask you what item you want to send to the convoy.
Thief units that have sword rank can use daggers.
Daggers are in general 1-2 range weapons, so your sword locked thieves have better range than in the original game.
Units that have thief skills will retain those skills even if they promote to classes that aren't thief classes.
You don't have to worry about choosing promotions for your thieves on fear that they would lose those skills.

Ballistas are regular classes instead of features of certain maps.
Your archers can promote into them, and will receive a ballista item upon promotion.

Cavaliers can only use one weapon type. Due to branch promotions that can vary depending on the unit.
Your cavaliers can end up wielding different weapons even if they start with the same weapon.

Some classes, for the purpose of effective damage, had their class type change (or added in some cases).
In the early game, you may find that Mogalls count as flyers and that spiders count as Horses. This applies to their promotions too.
Mogalls can use their personal Light Magic.
The Manakete class has a level cap of 30 instead of 20 like the other classes.
Mage Knights use Anima Magic and Swords instead of Anima Magic and Staves, and is no longer a promotion option for Troubadour.
Your Paladins can use Light Magic.
Knights can use more than one weapon type.
Wyvern Lords have Axes instead of swords.
Eirika's Great Lord class can use both combat and support Staves.
Ewan's promotions are special in the sense that he can keep Anima magic after promotion.
The dancer class counts as a promotion of Monk (Tethys already comes with T1 Monk skills).

Before a chapter's battle preparations, there's a base like in FE9 and FE10.
In the base you can give BEXP to your units, see base conversations, and activate support conversations.
When you select Continue, you'll be sent to the battle preparations screen.

The Turnwheel (a mechanic that was introduced in FE15) allows you to rewind to a previous point in a map. You have 7 charges that reset after a map.

In this game, poison is potentially more lethal and has been renamed to venom. Venom can stack, so the HP loss at the start of the turn can be deadly.
There's also the bleeding status, that makes you lose HP at the start of the turn and lose speed and it stacks.
These statuses cannot, however, deal lethal damage to player units or bosses.

You can no longer farm EXP and money in the arena. Instead, you'll be able to battle a miniboss that drops a weapon upon being defeated.

Armories and vendors have a wider variety of items, instead of regular steel, silver, etc. weapons.
You can enter secret shops during the main campaign from the overworld. You don't have to worry about missing out because you skipped a Secret Shop during its chapter.

The bad news is that the Silver Card doesn't exist here. The good news is that there are a few classes that learn a skill that reduces the shop prices.

Taken from Engage, this mechanic allows you to interact with the map after clearing a map. You can do the following:
Train with an ally. You can talk to an ally unit and raise a stat that you want for both your Lord and that unit.
You can train up to 4 times for chapter.
Talk with NPCs. You can talk with NPCs placed outside their houses that will give you BEXP.
(You can also visit villages or houses you didn't during the battle, though doing this will result in less overall BEXP)
Other interactions. If you see a shiny spark, and interact with it, it can produce events that can include small reinforcements.

If you cleared a level of the Tower or the Ruins, when you return you'll be given the option to skip that level.
You won't have to go through weak enemies when you want to grind in the Tower.
Clearing later levels of the Ruins will give you random weapons.
The Ruins aren't only populated by monsters now. There are human enemies there too. This means that Slayer can't solve all your problems there.
Both the Tower and the Ruins are now randomized. Enemy placements, classes, and inventory may vary. Enemies can also drop stat boosters and accessories.