Forgotten Ancient

Whenever a player casts a spell, you may put a +1/+1 counter on Forgotten Ancient.
At the beginning of your upkeep, you may move any number of +1/+1 counters from Forgotten Ancient onto other creatures.

Balduvian Rage

Target attacking creature gets +X/+0 until end of turn.
Draw a card at the beginning of the next turn's upkeep.

Forest

Blistering Firecat

Trample, haste
At the beginning of the end step, sacrifice Blistering Firecat.
Morph {R}{R} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Gorilla War Cry

Cast this spell only during combat before blockers are declared.
All creatures gain menace until end of turn. (They can't be blocked except by two or more creatures.)
Draw a card at the beginning of the next turn's upkeep.

Bestial Fury

Enchant creature
When Bestial Fury enters, draw a card at the beginning of the next turn's upkeep.
Whenever enchanted creature becomes blocked, it gets +4/+0 and gains trample until end of turn.

Gorilla Berserkers

Trample; rampage 2 (Whenever this creature becomes blocked, it gets +2/+2 until end of turn for each creature blocking it beyond the first.)
Gorilla Berserkers can't be blocked except by three or more creatures.

Act of Treason

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. (It can attack and {T} this turn.)

Hystrodon

Trample
Whenever Hystrodon deals combat damage to a player, you may draw a card.
Morph {1}{G}{G} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Giant Spectacle

Enchant creature
Enchanted creature gets +2/+1 and has menace.

Centaur Glade

{2}{G}{G}: Create a 3/3 green Centaur creature token.

Cathartic Reunion

As an additional cost to cast this spell, discard two cards.
Draw three cards.

Overrun

Creatures you control get +3/+3 and gain trample until end of turn. (Each of those creatures can deal excess combat damage to the player or planeswalker it's attacking.)

Kird Ape

Kird Ape gets +1/+2 as long as you control a Forest.

Brazen Scourge

Haste (This creature can attack and {T} as soon as it comes under your control.)

Flare

Flare deals 1 damage to any target.
Draw a card at the beginning of the next turn's upkeep.

Gorilla Shaman

{X}{X}{1}: Destroy target noncreature artifact with mana value X.

Earthquake

Earthquake deals X damage to each creature without flying and each player.

Elvish Aberration

{T}: Add {G}{G}{G}.
Forestcycling {2} ({2}, Discard this card: Search your library for a Forest card, reveal it, put it into your hand, then shuffle.)

Destructive Tampering

Choose one —
• Destroy target artifact.
• Creatures without flying can't block this turn.

Kari Zev, Skyship Raider

First strike, menace
Whenever Kari Zev, Skyship Raider attacks, create Ragavan, a legendary 2/1 red Monkey creature token. Ragavan enters tapped and attacking. Exile that token at end of combat.