When Craterhoof Behemoth enters the battlefield, creatures you control gain trample and get +X/+X until end of turn, where X is the number of creatures you control.
5 /
5
{G}{G}{G}{G}{G}{G}{G}{G}
Khalni Hydra
Creature - Hydra
This spell costs {G} less to cast for each green creature you control.
Trample
8 /
8
{5}{G}{G}{G}
Woodfall Primus
Creature - Treefolk Shaman
Trample
When Woodfall Primus enters the battlefield, destroy target noncreature permanent.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)
6 /
6
{8}{G}{G}{G}
Worldspine Wurm
Creature - Wurm
Trample
When Worldspine Wurm dies, create three 5/5 green Wurm creature tokens with trample.
When Worldspine Wurm is put into a graveyard from anywhere, shuffle it into its owner's library.