Nazgul, Servant of Sauron

Haste, Trample, First strike, Wither.
when Nazgul, Servant of Sauron, deals combat
damage to a creature, put a curse counter on that creature, at the beginning of your upkeep, put a
curse counter on that creature, if the amount of
curse counters on that creature is equal to that creatures toughness, gain control of target
creature, it is now a ring wraith in addition to its
other types.