Infernal Kirin

Flying
Whenever you cast a Spirit or Arcane spell, target player reveals their hand and discards all cards with that spell's mana value.

He Who Hungers

Flying
{1}, Sacrifice a Spirit: Target opponent reveals their hand. You choose a card from it. That player discards that card. Activate only as a sorcery.
Soulshift 4 (When this creature dies, you may return target Spirit card with mana value 4 or less from your graveyard to your hand.)

Scarmaker

Remove a ki counter from Scarmaker: Target creature gains fear until end of turn. (It can't be blocked except by artifact creatures and/or black creatures.)

Hired Muscle

Whenever you cast a Spirit or Arcane spell, you may put a ki counter on this creature.
At the beginning of the end step, if there are two or more ki counters on this creature, you may flip it.