Pyretic Ritual

Jet Medallion

Black spells you cast cost {1} less to cast.

Crucible of Worlds

Bubbling Muck

Until end of turn, whenever a player taps a Swamp for mana, that player adds an additional {B}.

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.)

Pyroblast

Choose one —
• Counter target spell if it's blue.
• Destroy target permanent if it's blue.

Lotus Petal

{T}, Sacrifice Lotus Petal: Add one mana of any color.

Cryptolith Rite

Creatures you control have "{T}: Add one mana of any color."

Red Elemental Blast

Choose one —
• Counter target blue spell.
• Destroy target blue permanent.

Rain of Filth

Until end of turn, lands you control gain "Sacrifice this land: Add {B}."

Skithiryx, the Blight Dragon

Flying
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
{B}: Skithiryx, the Blight Dragon gains haste until end of turn.
{B}{B}: Regenerate Skithiryx.