Pestilence, Rider Of The End

Apocalyptic (When this enters, sacrifice it unless
the number of cards in your library is equal to or
less than half your starting deck size, rounded down)
When Pestilence enters and when it attacks,
put a -1/-1 counter on up to one other target
creature and up to one target player gets a
poison counter, then proliferate. (Choose any
number of permanents and/or players, then give each
another counter of each kind already there.)