Pillars of Eternity II: Deadfire abilities

Abilities in are mostly class-specific, and are unlocked via an ability tree unique to each class. Other abilities can be learned by equipping items, completing quests, or as a result of certain character options.

Progression
Ability progression, and the amount of abilities learned differs slightly between classes.

Power levels
Class abilities are grouped by power level. As a character levels up, new power levels are unlocked and more powerful abilities may be learned.
 * Single class - New ability power levels are learned every second level from level 1 (1, 3, 5, 7, 9, 11, 13), then every third level from level 13 (16, 19).
 * Multi class - Characters may only learn up to (and including) power level 7 abilities, and unlock a new power level every third level from level 1 (1, 4, 7, 10, 13, 16, 19).

New abilities
Upon level up, the character must select a certain number of abilities to learn, and may pick from any currently-unlocked power level, and on either active or passive abilities.
 * At character creation, select one 1st level ability (active only).
 * Some classes automatically learn unique "Core" abilities at character creation.
 * Some subclasses automatically grant a new ability at each power level. This ability does not deduct from the amount of abilities that can be learned.
 * At every character level, new abilities must be picked from the classes ability tree:
 * Single class - Pick two abilities at every level where a new power level is unlocked excluding the first (3, 5, 7, 9, 11, 13, 16, 19), and one ability at all other levels (1, 2, 4, 6, 8, 10, 12, 14, 15, 17, 18, 20) for a total of 28 abilities at max level.
 * Multi class - Pick one ability from the ability tree of either class at all levels where a new power level isn't unlocked (2, 3, 5, 6, 8, 9, 11, 12, 14, 15, 17, 18, 20) and two abilities (one for each class) at all levels where a new power level is unlocked (1, 4, 7, 10, 13, 16, 19) for a total of 27 abilities at max level.
 * At character creation, select two weapon proficiencies.
 * One weapon proficiency must be selected at every fourth level after level 1 (4, 8, 12, 16, 20)

Talents
Talents are not prominently featured in, and now fall under the same umbrella as passive abilities. Some unique permanent bonuses found in-game are now classed as status effects.

Spells
Spells are simply abilities cast by spellcasters (Druids, Priests, and Wizards). The main difference between spells and (active) abilties is that the use of spells are limited to the amount of casts that can be made at each power level, while abilities operate independently of each other and have an associated resource cost.

Proficiencies
Proficiencies are unique abilities that are available when the proficient weapon or shield is equipped. All proficiencies grant certain bonuses, and a modal ability that may be toggled on or off depending on the wielder's needs.

Keywords
Many abilities (and items) have a number of keywords associated with them. The presence of keywords indicates that the ability may be modified or affected in some way by effects that target that keyword. Some keywords are used internally to keep track of complex effects.

Counters
A counter is any ability or effect that removes or prevents another category of effects when applied. Abilities that have counter keywords are able to have their effects completely nullified by the effects of abilities with those keywords. Only abilities with a duration, or with ongoing status effects can be countered.

For example, the beneficial effects of a paladins Eternal Devotion (keyword "Fire") will be cancelled if any Frost or Water-keyword ability hits the paladin (e.g. Hail Storm). This also applies to hazard AoE surfaces, for example casting a Wall of Frost over a Wall of Flame will remove the frost wall and keep the flame wall, and vice versa.

Counter keywords to current effects are shown with the symbol when a character is hovered over. When an effect is removed as a result of a counter, a nondescript "down arrow" is shown in the combat log. When an effect blocks or cancels out an incoming effect, the text "The effect canceled with x" appears in the combat log, where x is the effect that was negated.

Counters factor in whether the applied effect is a beneficial or hostile effect. Beneficial effects are only able to be countered by hostile effects. For example, if an ally casts Moonwell over your Flame Shield, this does not remove the Flame Shield despite them being counters. However if you are hit by a hostile Water-keyword ability (e.g. Boiling Spray), you will take no damage but your Flame Shield will be removed. Basically, beneficial effects applied to your party cannot be accidentally canceled out by other beneficial effects.

Most of the existing counters are two-way (e.g. Fire/Water/Frost), which can make it confusing whether an effect is negated by or negates an incoming effect. Oftentimes both will occur and the effects will effectively cancel eachother out, but this varies depending on the ability. Keep in mind that effects are always applied based on the order they are cast, so counters are always applied over existing effects. Non two-way keywords (e.g. Antidote) are always applied over the keyword that it counters, e.g. (Poison).

Stacking or repeating effects have their stacks cleared by a countering effect, but will not remove the actual ability. This means that while the current effect of a "pulsing" ability like Moonwell may be removed, the actual ability instance will still continue to apply effects at the next interval.

Inspirations and afflictions of the same attribute (e.g. Dexterity, Perception) automatically counter and remove or prevent the application of the corresponding group of afflictions for that attribute.

Only a handful of counters exist:
 * Fire → Water, Frost
 * Frost → Fire
 * Poison → Antidote
 * Water → Fire