Sensei's Divining Acorn

{1}: Say: "The squirrels are coming!" If you
do, create an Acorn token. (It's an artifact
with "{1}, {t}, Sacrifice this artifact: Put a
+1/+1 counter on target Squirrel you control.")
{t}, Sacrifice an Acorn: Create a 1/1 green
Squirrel creature token, then put Sensei's
Divining Acorn on top of your library.