Verdant Eidolon

{G}, Sacrifice Verdant Eidolon: Add three mana of any one color.
Whenever you cast a multicolored spell, you may return Verdant Eidolon from your graveyard to your hand.

Fateful Showdown

Fateful Showdown deals damage to any target equal to the number of cards in your hand. Discard all the cards in your hand, then draw that many cards.

Manamorphose

Add two mana in any combination of colors.
Draw a card.

Sandstorm Eidolon

{R}, Sacrifice Sandstorm Eidolon: Target creature can't block this turn.
Whenever you cast a multicolored spell, you may return Sandstorm Eidolon from your graveyard to your hand.

Wild Cantor

({R/G} can be paid with either {R} or {G}.)
Sacrifice Wild Cantor: Add one mana of any color.

Desperate Ritual

Add {R}{R}{R}.
Splice onto Arcane {1}{R} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Heartwarming Redemption

Discard all the cards in your hand, then draw that many cards plus one. You gain life equal to the number of cards in your hand.

Entropic Eidolon

{B}, Sacrifice Entropic Eidolon: Target player loses 1 life and you gain 1 life.
Whenever you cast a multicolored spell, you may return Entropic Eidolon from your graveyard to your hand.

Mountain

Enigma Eidolon

{U}, Sacrifice Enigma Eidolon: Target player mills three cards.
Whenever you cast a multicolored spell, you may return Enigma Eidolon from your graveyard to your hand.