Heartstone

Activated abilities of creatures cost {1} less to activate. This effect can't reduce the mana in that cost to less than one mana.

Gruul Signet

Ichor Wellspring

When this artifact enters or is put into a graveyard from the battlefield, draw a card.

Sol Ring

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Rakdos Signet

Anrakyr the Traveller

Lord of the Pyrrhian Legions — Whenever Anrakyr the Traveller attacks, you may cast an artifact spell from your hand or graveyard by paying life equal to its mana value rather than paying its mana cost.

Cryptek

{1}{B}, {T}: Choose another target artifact creature you control. When that creature dies this turn, return it to the battlefield tapped under your control.

Golgari Signet

Lokhust Heavy Destroyer

Flying
Enmitic Exterminator — When this creature enters, each player sacrifices a creature of their choice.
Unearth {5}{B}{B}{B} ({5}{B}{B}{B}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Shattergang Brothers

{2}{B}, Sacrifice a creature: Each other player sacrifices a creature.
{2}{R}, Sacrifice an artifact: Each other player sacrifices an artifact.
{2}{G}, Sacrifice an enchantment: Each other player sacrifices an enchantment.

Psychomancer

Flying
Harbinger of Despair — Whenever this creature or another nontoken artifact you control is put into a graveyard from the battlefield or is put into exile from the battlefield, target opponent loses 1 life and you gain 1 life.