Wild Nacatl

This creature gets +1/+1 as long as you control a Mountain.
This creature gets +1/+1 as long as you control a Plains.

Wooded Foothills

{T}, Pay 1 life, Sacrifice this land: Search your library for a Mountain or Forest card, put it onto the battlefield, then shuffle.

Atarka's Command

Choose two —
• Your opponents can't gain life this turn.
• Atarka's Command deals 3 damage to each opponent.
• You may put a land card from your hand onto the battlefield.
• Creatures you control get +1/+1 and gain reach until end of turn.

Spark Elemental

Trample, haste (This creature can deal excess combat damage to the player or planeswalker it's attacking. This creature can attack and {T} as soon as it comes under your control.)
At the beginning of the end step, sacrifice this creature.

Pelt Collector

Whenever another creature you control enters or dies, if that creature's power is greater than this creature's, put a +1/+1 counter on this creature.
As long as this creature has three or more +1/+1 counters on it, it has trample.

Experiment One

Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)
Remove two +1/+1 counters from this creature: Regenerate it. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Windswept Heath

{T}, Pay 1 life, Sacrifice this land: Search your library for a Forest or Plains card, put it onto the battlefield, then shuffle.

Sonic Seizure

As an additional cost to cast this spell, discard a card at random.
Sonic Seizure deals 3 damage to any target.