Argothian Sprite

Argothian Sprite can't be blocked by artifact creatures.
{7}: Put two +1/+1 counters on Argothian Sprite.

Gravel-Hide Goblin

{3}{G}: Gravel-Hide Goblin gets +2/+2 until end of turn.

Agatha of the Vile Cauldron

Activated abilities of creatures you control cost {X} less to activate, where X is Agatha of the Vile Cauldron's power. This effect can't reduce the mana in that cost to less than one mana.
{4}{R}{G}: Other creatures you control get +1/+1 and gain trample and haste until end of turn.

Domesticated Hydra

{X}{G}{G}{G}: Monstrosity X. (If this creature isn't monstrous, put X +1/+1 counters on it and it becomes monstrous.)
As long as Domesticated Hydra is monstrous, it has trample.

Cinder Elemental

{X}{R}, {T}, Sacrifice Cinder Elemental: It deals X damage to any target.

Iridescent Blademaster

{3}{G}: Iridescent Blademaster gets +2/+2 until end of turn.

Almighty Brushwagg

Trample
{3}{G}: Almighty Brushwagg gets +3/+3 until end of turn.

Feral Animist

{3}: Feral Animist gets +X/+0 until end of turn, where X is its power.

Devotee of Strength

{4}{G}: Target creature gets +2/+2 until end of turn.

Cogwork Assembler

{7}: Create a token that's a copy of target artifact. That token gains haste. Exile it at the beginning of the next end step.

Flamewave Invoker

{7}{R}: Flamewave Invoker deals 5 damage to target player or planeswalker.

Dawnhart Mentor

When Dawnhart Mentor enters, create a 1/1 white Human creature token.
Coven — {5}{G}: Target creature you control gets +3/+3 and gains trample until end of turn. Activate only if you control three or more creatures with different powers.

Atarka Beastbreaker

Formidable — {4}{G}: Atarka Beastbreaker gets +4/+4 until end of turn. Activate only if creatures you control have total power 8 or greater.