The Green Lady

Whenever The Green Lady becomes target of a
spell or ability controlled by an opponent, exile
her and reveal cards from the top of your library
until you reveal a creature card. Put that card on
the battlefield and shuffle The Green Lady into
your library after that.
Deathlords you control have Undying.
Legends tell of a Sideral that went out to discover
how to truly destroy a Deathlord and was corrupted.