Hangarback Walker

Hangarback Walker enters with X +1/+1 counters on it.
When Hangarback Walker dies, create a 1/1 colorless Thopter artifact creature token with flying for each +1/+1 counter on Hangarback Walker.
{1}, {T}: Put a +1/+1 counter on Hangarback Walker.

Stonecoil Serpent

Reach, trample, protection from multicolored
Stonecoil Serpent enters with X +1/+1 counters on it.

Flash

You may put a creature card from your hand onto the battlefield. If you do, sacrifice it unless you pay its mana cost reduced by {2}.

Island

Simian Spirit Guide

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

Disciple of the Vault

Whenever an artifact is put into a graveyard from the battlefield, you may have target opponent lose 1 life.

Lotus Petal

{T}, Sacrifice Lotus Petal: Add one mana of any color.

Chamber Sentry

Chamber Sentry enters with a +1/+1 counter on it for each color of mana spent to cast it.
{X}, {T}, Remove X +1/+1 counters from Chamber Sentry: It deals X damage to any target.
{W}{U}{B}{R}{G}: Return Chamber Sentry from your graveyard to your hand.

Mystical Tutor

Search your library for an instant or sorcery card, reveal it, then shuffle and put that card on top.

Elvish Spirit Guide

Exile Elvish Spirit Guide from your hand: Add {G}.

Protean Hulk

When Protean Hulk dies, search your library for any number of creature cards with total mana value 6 or less, put them onto the battlefield, then shuffle.

Gemstone Caverns

If Gemstone Caverns is in your opening hand and you're not the starting player, you may begin the game with Gemstone Caverns on the battlefield with a luck counter on it. If you do, exile a card from your hand.
{T}: Add {C}. If Gemstone Caverns has a luck counter on it, instead add one mana of any color.

Walking Ballista

Walking Ballista enters with X +1/+1 counters on it.
{4}: Put a +1/+1 counter on Walking Ballista.
Remove a +1/+1 counter from Walking Ballista: It deals 1 damage to any target.

Shifting Wall

Defender (This creature can't attack.)
Shifting Wall enters with X +1/+1 counters on it.

Phyrexian Marauder

Phyrexian Marauder enters with X +1/+1 counters on it.
Phyrexian Marauder can't block.
Phyrexian Marauder can't attack unless you pay {1} for each +1/+1 counter on it.