Last March of the Ents

Search your library for X forests and put
them onto the battlefield tapped. Put X
+1/+1 counters on those forests, they
become Ent creatures with trample and last strike. They are still lands.
"Hroom, hm, come, my friends. The Ents are
going to war. It is likely that we go to our doom.
The last march of the Ents." -Treebeard