Arcane Signet

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

Dark Ritual

Discord, Lord of Disharmony

Flying
At the beginning of your end step, choose a random nonland Magic card name. Until your next end step, you may cast a copy of a spell with that name, and mana of any type can be spent to cast it. If you cast a spell this way, copy this ability if Discord is on the battlefield.

Seething Song

Neheb, the Eternal

Afflict 3 (Whenever this creature becomes blocked, defending player loses 3 life.)
At the beginning of your postcombat main phase, add {R} for each 1 life your opponents have lost this turn.

Mana Geyser

Add {R} for each tapped land your opponents control.

Rakdos Signet

Mana Flare

Whenever a player taps a land for mana, that player adds one mana of any type that land produced.

Sol Ring

Thran Dynamo

Firemind Vessel

Firemind Vessel enters the battlefield tapped.
{T}: Add two mana of different colors.

Vessel of Volatility

{1}{R}, Sacrifice Vessel of Volatility: Add {R}{R}{R}{R}.

Fellwar Stone

{T}: Add one mana of any color that a land an opponent controls could produce.