Tidal, Waveborne Marauder

Spells you cast that you don’t own have casualty 2.

Whenever an attacking creature you control dies,
choose a zone that hasn’t been chosen this turn
from among the defending player's graveyard,
hand, and library. Exile a card at random from the
chosen zone. You may cast that card for as long as
it remains exiled, and mana of any type can be
spent to cast it.