Voracious Hydra

Trample
This creature enters with X +1/+1 counters on it.
When this creature enters, choose one —
• Double the number of +1/+1 counters on this creature.
• This creature fights target creature you don't control.

Giant Growth

Target creature gets +3/+3 until end of turn.

Greenwood Sentinel

Vigilance (Attacking doesn't cause this creature to tap.)

Barkhide Troll

This creature enters with a +1/+1 counter on it.
{1}, Remove a +1/+1 counter from this creature: This creature gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

Rabid Bite

Target creature you control deals damage equal to its power to target creature you don't control.

Gnarlback Rhino

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
Whenever you cast a spell that targets this creature, draw a card.

Silverback Shaman

Trample
When this creature dies, draw a card.

Season of Growth

Whenever a creature you control enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.)
Whenever you cast a spell that targets a creature you control, draw a card.

Oakenform

Enchant creature
Enchanted creature gets +3/+3.

Aggressive Mammoth

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
Other creatures you control have trample.

Forest

Gargos, Vicious Watcher

Vigilance
Hydra spells you cast cost {4} less to cast.
Whenever a creature you control becomes the target of a spell, Gargos fights up to one target creature you don't control.

Growth Cycle

Target creature gets +3/+3 until end of turn. It gets an additional +2/+2 until end of turn for each card named Growth Cycle in your graveyard.

Wakeroot Elemental

{G}{G}{G}{G}{G}: Untap target land you control. It becomes a 5/5 Elemental creature with haste. It's still a land. (This effect lasts as long as that land remains on the battlefield.)