Companions are a type of minion with special mechanics used primarily the Primalist class. By default, you can have 2 companions active at once.
All minion stats and effects apply to companions, but there are effects that only benefit companions.
After using a skill to summon a companion, the summon skill will be replaced by a companion ability, which is specific to the companion summoned.
If you can summon multiple of the same companion, you must summon the maximum number or reach your companion limit before the ability will change.
When a companion’s health is reduced to zero, it enters a Downed state rather than dying. Being close to a downed companion will revive it, but if you wait too long the companion will die and must be summoned again.