Gruul Locket

{T}: Add {R} or {G}.
{R/G}{R/G}{R/G}{R/G}, {T}, Sacrifice this artifact: Draw two cards.

Lavabrink Floodgates

{T}: Add {R}{R}.
At the beginning of each player's upkeep, that player may put a doom counter on this artifact or remove a doom counter from it. Then if it has three or more doom counters on it, sacrifice this artifact. When you do, it deals 6 damage to each creature.

Heart of Ramos

{T}: Add {R}.
Sacrifice this artifact: Add {R}.

Firewild Borderpost

You may pay {1} and return a basic land you control to its owner's hand rather than pay this spell's mana cost.
This artifact enters tapped.
{T}: Add {R} or {G}.

Atarka Monument

{T}: Add {R} or {G}.
{4}{R}{G}: This artifact becomes a 4/4 red and green Dragon artifact creature with flying until end of turn.

Gruul Keyrune

{T}: Add {R} or {G}.
{R}{G}: This artifact becomes a 3/2 red and green Beast artifact creature with trample until end of turn.

Mox Opal

Metalcraft — {T}: Add one mana of any color. Activate only if you control three or more artifacts.

Troll-Horn Cameo

Gruul Signet

Gruul Cluestone

{T}: Add {R} or {G}.
{R}{G}, {T}, Sacrifice this artifact: Draw a card.

Talisman of Impulse

{T}: Add {C}.
{T}: Add {R} or {G}. This artifact deals 1 damage to you.

Moss Diamond

This artifact enters tapped.
{T}: Add {G}.