Dasha, Spirit of Vengeance

This spell cost {1} less to cast for each creature
in your graveyard.
Flying, Deathtouch
Whenever you cast Dasha, Spirit of Vengeance,
you may destroy up to x target creatures where
x is equal to the amount of times you've cast your commander form the command zone this game.
"They that die, pay their debts."
- Orzhov fine print