Does not directly add content for the player to experience, but adds many many modding tools, such as:
Ability comps that define AI usage of the ability, alter cooldowns dynamically, establish minimum stat prerequisites, or perform effects (alter Need levels, create a thought if the ability has/hasn't been used recently, create a 'linked hediff' between the caster and target, etc.)
Aura hediffs that are more performant and customizable than the 'command auras' introduced in Ideology
Hediffs that cause attacks and/or psycasts to have additional effects, such as extra damage, hediff infliction, thought infliction, mental state infliction, etc.
Damage-response hediffs which occur in a customizable series; these can negate and/or retaliate to damage of various types
A system for "delayed resurrection", as well as a fix that enables resurrected corpses that are on a caravan or in a grave to actually resurrect into that caravan/grave rather than just disappearing
A wider variety of permit tools, such as permits that affect targeted pawns, drop items from specific categories, or the like