underworld Wyrm

this card costs {1} less to cast for each creature card in each graveyard whenever a creature you control dies and underworld Wyrmis in your hand and put a death counter on it when underworld Wyrm enters the battlefield underworld Wyrm gets {x} -1-1 counters for each death counter on it when underworld Wyrm enters the battlefield your opponent sacrifices {x} creatures where {x} is how many death counters are on underworld Wyrm
6} you and a target opponent sacrifices a creature you may cast this from you