Ancient Den

Great Furnace

Leonin Bola

Equipped creature has "{T}, Unattach Leonin Bola: Tap target creature."
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery. This card enters unattached and stays on the battlefield if the creature leaves.)

Claws of Valakut

Enchant creature
Enchanted creature gets +1/+0 for each Mountain you control and has first strike.

Welding Jar

Sacrifice Welding Jar: Regenerate target artifact.

Sylvok Replica

{G}, Sacrifice Sylvok Replica: Destroy target artifact or enchantment.

Smash

Spell Pierce

Counter target noncreature spell unless its controller pays {2}.

Ancient Grudge

Destroy target artifact.
Flashback {G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

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.

Gearseeker Serpent

This spell costs {1} less to cast for each artifact you control.
{5}{U}: Gearseeker Serpent can't be blocked this turn.

Temur Battle Rage

Target creature gains double strike until end of turn.
Ferocious — That creature also gains trample until end of turn if you control a creature with power 4 or greater.

Circle of Protection: Black

{1}: The next time a black source of your choice would deal damage to you this turn, prevent that damage.

Galvanic Blast

Galvanic Blast deals 2 damage to any target.
Metalcraft — Galvanic Blast deals 4 damage instead if you control three or more artifacts.

Prophetic Prism

When Prophetic Prism enters, draw a card.
{1}, {T}: Add one mana of any color.

Smash to Smithereens

Destroy target artifact. Smash to Smithereens deals 3 damage to that artifact's controller.

Shattering Pulse

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.)
Destroy target artifact.

Atog

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

Circle of Protection: Green

{1}: The next time a green source of your choice would deal damage to you this turn, prevent that damage.

Seat of the Synod

Ray of Revelation

Destroy target enchantment.
Flashback {G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Thraben Inspector

When Thraben Inspector enters, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Darksteel Citadel

Hydroblast

Choose one —
• Counter target spell if it's red.
• Destroy target permanent if it's red.

Myr Enforcer

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

Somber Hoverguard

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

Muddle the Mixture

Counter target instant or sorcery spell.
Transmute {1}{U}{U} ({1}{U}{U}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)