Counterspell

Terrarion

Terrarion enters tapped.
{2}, {T}, Sacrifice Terrarion: Add two mana in any combination of colors.
When Terrarion is put into a graveyard from the battlefield, draw a card.

Manamorphose

Add two mana in any combination of colors.
Draw a card.

Ichor Wellspring

When Ichor Wellspring enters or is put into a graveyard from the battlefield, draw a card.

Seat of the Synod

Fling

As an additional cost to cast this spell, sacrifice a creature.
Fling deals damage equal to the sacrificed creature's power to any target.

Great Furnace

Shield Sphere

Defender
Whenever Shield Sphere blocks, put a -0/-1 counter on it.

Darksteel Citadel

Chromatic Star

{1}, {T}, Sacrifice Chromatic Star: Add one mana of any color.
When Chromatic Star is put into a graveyard from the battlefield, draw a card.

Lotus Petal

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

Atog

Sacrifice an artifact: Atog gets +2/+2 until end of turn.

Thoughtcast

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Draw two cards.