Sypha, Revenge Incarnate

Indestructible, Deathtouch, Vanishing 3, Flash
Whenever a creature you control is reduced to 0 toughness or below from combat damage, if that creature attacked this turn, destroy a creature that
dealt damage to it this turn.
When Sypha vanishes, shuffle it back into your library, and create a 1/1 green Serpent creature
token.