Food Chain

Exile a creature you control: Add X mana of any one color, where X is 1 plus the exiled creature's mana value. Spend this mana only to cast creature spells.

Squee, the Immortal

You may cast Squee, the Immortal from your graveyard or from exile.

Mox Amber

{T}: Add one mana of any color among legendary creatures and planeswalkers you control.

Ragavan, Nimble Pilferer

Whenever Ragavan, Nimble Pilferer deals combat damage to a player, create a Treasure token and exile the top card of that player's library. Until end of turn, you may cast that card.
Dash {1}{R} (You may cast this spell for its dash cost. If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.)

Mox Opal

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

Shadowspear

Equipped creature gets +1/+1 and has trample and lifelink.
{1}: Permanents your opponents control lose hexproof and indestructible until end of turn.
Equip {2}

Reki, the History of Kamigawa

Whenever you cast a legendary spell, draw a card.

Instrument of the Bards

At the beginning of your upkeep, you may put a harmony counter on Instrument of the Bards.
{3}{G}, {T}: Search your library for a creature card with mana value equal to the number of harmony counters on Instrument of the Bards, reveal it, and put it into your hand. If that card is legendary, create a Treasure token. Then shuffle.

Rograkh, Son of Rohgahh

First strike, menace, trample
Partner (You can have two commanders if both have partner.)