Isaak, Skeletal Scholar

Ward {2}

{u/b}{u/b}{t}: Cast an Instant or Sorcery card from
your graveyard, then exile that card.

Whenever you cast an instant or sorcery card
from your Graveyard, you may play a Skeleton
creature card from your Graveyard with mana
cost less than or equal to the cost of the spell
cast without paying its mana cost.