Bonesplitter Sliver

Seal of Primordium

Sacrifice Seal of Primordium: Destroy target artifact or enchantment.

Gathan Raiders

Hellbent — Gathan Raiders gets +2/+2 as long as you have no cards in hand.
Morph—Discard a card. (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Penumbra Spider

Reach
When Penumbra Spider dies, create a 2/4 black Spider creature token with reach.

Lava Spike

Lava Spike deals 3 damage to target player or planeswalker.

Mogg War Marshal

Echo {1}{R} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)
When Mogg War Marshal enters or dies, create a 1/1 red Goblin creature token.

Spinneret Sliver

Brute Force

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

Terramorphic Expanse

{T}, Sacrifice Terramorphic Expanse: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Virulent Sliver

All Sliver creatures have poisonous 1. (Whenever a Sliver deals combat damage to a player, that player gets a poison counter. A player with ten or more poison counters loses the game.)

Forest

Bloodbraid Elf

Haste (This creature can attack and {T} as soon as it comes under your control.)
Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)

Cloud Key

As Cloud Key enters, choose artifact, creature, enchantment, instant, or sorcery.
Spells you cast of the chosen type cost {1} less to cast.

Reiterate

Buyback {3} (You may pay an additional {3} as you cast this spell. If you do, put this card into your hand as it resolves.)
Copy target instant or sorcery spell. You may choose new targets for the copy.

Uktabi Drake

Flying, haste
Echo {1}{G}{G} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)

Eternal Witness

When Eternal Witness enters, you may return target card from your graveyard to your hand.

Strength in Numbers

Until end of turn, target creature gains trample and gets +X/+X, where X is the number of attacking creatures.

Mountain

Thornweald Archer

Reach (This creature can block creatures with flying.)
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Phantom Wurm

Phantom Wurm enters with four +1/+1 counters on it.
If damage would be dealt to Phantom Wurm, prevent that damage. Remove a +1/+1 counter from Phantom Wurm.

Skirk Shaman

Skirk Shaman can't be blocked except by artifact creatures and/or red creatures.

Simian Spirit Guide

Exile Simian Spirit Guide from your hand: Add {R}.

Courser of Kruphix

Play with the top card of your library revealed.
You may play lands from the top of your library.
Landfall — Whenever a land you control enters, you gain 1 life.