Reactions

Insistent Education. The Aggregation of Madness latches onto a creatures mind, forcing unwanted knowledge upon it. The target creature must make a Wisdom saving throw or become Frightened until the end of its next turn. It must make another Wisdom saving throw at the start of its next turn, ending the effect on a success. If the target is already Frightened, Charmed, or Stunned, it instead immediately suffers 3d6 Psychic damage.

Channelled Cantrip. The Aggregation of Madness uses its reaction to channel a Cantrip cast by its bonded Shaman through itself. Cantrips cast in this way are treated as though the caster is half the bonded Shaman's current level, rounded down, for the purposes of damage calculations or for determining the number of attacks made.
i.e. Fire Bolt would deal 1d10 damage up to Level 9, and at Level 10, it would increase to 2d10.

Empowered Channelling. The Aggregation of Madness uses its reaction to channel a Spell cast by its bonded Shaman through itself. If this is used to channel a Cantrip, it does not suffer the aformentioned weakning.