Deathwish Witch

When Deathwish Witch enters the battlefield, X number of target creatures have deathtouch until end of turn.
When Deathwish Witch leaves the battlefield, {t} a creature you control: If a creature was tapped in this way you may cast a black or green instant or sorcery with a converted mana cost of 2 or less from your hand without paying the mana cost.