Mana Flare

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

Comet Storm

Multikicker {1} (You may pay an additional {1} any number of times as you cast this spell.)
Choose any target, then choose another target for each time this spell was kicked. Comet Storm deals X damage to each of them.

War's Toll

Whenever an opponent taps a land for mana, tap all lands that player controls.
If a creature an opponent controls attacks, all creatures that opponent controls attack if able.

Manabarbs

Whenever a player taps a land for mana, Manabarbs deals 1 damage to that player.

Sol Ring

Mountain

Flare of Duplication

You may sacrifice a nontoken red creature rather than pay this spell's mana cost.
Copy target instant or sorcery spell. You may choose new targets for the copy.

Worn Powerstone

Worn Powerstone enters the battlefield tapped.
{T}: Add {C}{C}.

Mana Geyser

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

Ruby Medallion

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

Pyroblast

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

Cinder Wall

Defender
When Cinder Wall blocks, destroy it at end of combat.

Faithless Looting

Draw two cards, then discard two cards.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)