Omen Hawker

{T}: Add {C}{U}. Spend this mana only to activate abilities.

Island

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Scalding Tarn

{T}, Pay 1 life, Sacrifice Scalding Tarn: Search your library for an Island or Mountain card, put it onto the battlefield, then shuffle.

Steam Vents

({T}: Add {U} or {R}.)
As Steam Vents enters, you may pay 2 life. If you don't, it enters tapped.

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.

Serum Visions

Goblin Cannon

{2}: Goblin Cannon deals 1 damage to any target. Sacrifice Goblin Cannon.

Counterspell

Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.

Mountain

Freed from the Real

Enchant creature
{U}: Tap enchanted creature.
{U}: Untap enchanted creature.

Fog Bank

Defender (This creature can't attack.)
Flying
Prevent all combat damage that would be dealt to and dealt by this creature.