General Ferrous Rokiric

Hexproof from monocolored
Whenever you cast a multicolored spell, create a 4/4 red and white Golem artifact creature token.

Mountain

Sol Ring

Boros Signet

Otharri, Suns' Glory

Flying, lifelink, haste
Whenever Otharri, Suns' Glory attacks, you get an experience counter. Then create a 2/2 red Rebel creature token that's tapped and attacking for each experience counter you have.
{2}{R}{W}, Tap an untapped Rebel you control: Return Otharri from your graveyard to the battlefield tapped.

Lightning Helix

Lightning Helix deals 3 damage to any target and you gain 3 life.

Blade Historian

Attacking creatures you control have double strike.

Neyali, Suns' Vanguard

Attacking tokens you control have double strike.
Whenever one or more tokens you control attack a player, exile the top card of your library. During any turn you attacked with a token, you may play that card.

Talisman of Conviction

{T}: Add {C}.
{T}: Add {R} or {W}. Talisman of Conviction deals 1 damage to you.

Balefire Liege

Other red creatures you control get +1/+1.
Other white creatures you control get +1/+1.
Whenever you cast a red spell, Balefire Liege deals 3 damage to target player or planeswalker.
Whenever you cast a white spell, you gain 3 life.

Arcane Signet

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

Obsidian Obelisk

Obsidian Obelisk enters tapped.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a multicolored spell.