Swamp Keeper

Morph {3}{b}{b} (You may cast this face down
as a 2/2 creature for {3}. Turn it face up any
time for its morph cost.)
When Swamp Keeper is turned face up during
combat on your opponent's turn, if you shout
"GET OUT OF MY SWAMP", it gains +10/+10 and "This creature can block any number of
creatures" until end of turn. Otherwise, put a
+1/+1 counter on it.
Shrek never wants Troglodytes in his swamp