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.

Counterbalance

Whenever an opponent casts a spell, you may reveal the top card of your library. If you do, counter that spell if it has the same mana value as the revealed card.

Ajani's Pridemate

Whenever you gain life, put a +1/+1 counter on this creature.

Counterspell

Island

Ajani's Welcome

Whenever a creature you control enters, you gain 1 life.

Render Silent

Counter target spell. Its controller can't cast spells this turn.

Plains

Auriok Champion

Protection from black and from red
Whenever another creature enters, you may gain 1 life.

Dovin's Veto

This spell can't be countered.
Counter target noncreature spell.

Flooded Strand

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

Aura Blast

Nimbus Maze

{T}: Add {C}.
{T}: Add {W}. Activate only if you control an Island.
{T}: Add {U}. Activate only if you control a Plains.

Bond of Discipline

Tap all creatures your opponents control. Creatures you control gain lifelink until end of turn.

Heliod, Sun-Crowned

Indestructible
As long as your devotion to white is less than five, Heliod isn't a creature.
Whenever you gain life, put a +1/+1 counter on target creature or enchantment you control.
{1}{W}: Another target creature gains lifelink until end of turn.

Tundra

Enlightened Tutor

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