Reactions

Deflect Attack. The Obelisk of Protection imposes a 1d4 penalty on the attack roll of one creature within its Aura of Aegis, provided the attack roll is against a creature other than the Pillar of Protection. This can be declared after the attack roll has been made but before damage calculations.

Channelled Cantrip. The Obelisk of Protection 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 Obelisk of Protection 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.