Aelfatava Death Brother

When Aelfatava Death Brother enters the
battlefield, you may search your library and
reveal a card named Aelfatava Blood Brother.
Shuffle your library and put it on top.
Nightfall: Aelfatava Death Brother gains +1/+1
and Deathtouch until end of turn." (Nightfall,
triggers the first time a Swamp or mono-Black
creature enters the battlefield under your control.)
"I am sworn to kill for my brothers."