You may exile a red card from your hand rather than pay this spell's mana cost.

Pyrokinesis deals 4 damage divided as you choose among any number of target creatures.

If you control a Plains, you may tap an untapped creature you control rather than pay this spell's mana cost.

Creatures you control get +1/+1 until end of turn.

If an opponent cast a red instant or sorcery spell this turn, you may pay rather than pay this spell's mana cost.

Prevent the next 3 damage that a source of your choice would deal to you and/or permanents you control this turn. If damage is prevented this way, Refraction Trap deals that much damage to any target.

You may exile a white card from your hand rather than pay this spell's mana cost.

Choose a color. All creatures gain protection from the chosen color until end of turn.

If an opponent cast a blue spell this turn, you may pay rather than pay this spell's mana cost.

Change the target of target spell with a single target.

If you control a Swamp, you may pay 2 life rather than pay this spell's mana cost.

Target creature gets +2/+0 until end of turn.

When Runeforge Champion enters, you may search your library and/or graveyard for a Rune card, reveal it, and put it into your hand. If you search your library this way, shuffle.

You may pay rather than pay the mana cost for Rune spells you cast.

+1: Dragon cards in your hand perpetually gain "This spell costs less to cast", and "You may pay rather than pay this spell's mana cost, where X is its mana value."

0: Conjure a card named Shivan Dragon into your hand.

−2: Sarkhan, Wanderer to Shiv deals 3 damage to target creature.

Flying

You may cast Scourge of Nel Toth from your graveyard by paying and sacrificing two creatures rather than paying its mana cost.

You may pay and tap four untapped creatures you control with flying rather than pay this spell's mana cost.

Flying, lifelink

Other creatures you control with flying have indestructible. (Damage and effects that say "destroy" don't destroy them.)

You may exile a black card with mana value X from your hand rather than pay this spell's mana cost.

Target creature gets -X/-X until end of turn.

If you control a Forest, rather than pay this spell's mana cost, you may have each other player gain 5 life.

You may discard a Forest card rather than pay this spell's mana cost.

Prevent all combat damage that would be dealt by unblocked creatures this turn.

If you control a Swamp, you may pay 4 life rather than pay this spell's mana cost.

Destroy target nonblack creature. It can't be regenerated.

You may exile the top three black cards of your graveyard rather than pay this spell's mana cost.

Spinning Darkness deals 3 damage to target nonblack creature. You gain 3 life.

You may pay and exile a creature card from your graveyard rather than pay this spell's mana cost.

Flying

You may exile two white cards from your hand rather than pay this spell's mana cost.

Destroy all creatures.

You may tap three untapped Dwarves you control rather than pay this spell's mana cost.

At the beginning of each end step, if a land you controlled was put into a graveyard from the battlefield this turn, reveal the top four cards of your library. You may put any number of Dwarf cards from among them into your hand. Put the rest on the bottom of your library in a random order.

You may sacrifice a Mountain rather than pay this spell's mana cost.

Thunderclap deals 3 damage to target creature.

You may return an Island you control to its owner's hand rather than pay this spell's mana cost.

You may tap or untap target creature.

You may exile a black card from your hand rather than pay this spell's mana cost.

Target player reveals their hand. You choose a nonland card from it. That player discards that card.

You may pay and return a basic land you control to its owner's hand rather than pay this spell's mana cost.

Veinfire Borderpost enters tapped.

: Add or .

You may exile a green card from your hand rather than pay this spell's mana cost.

Flash

Forestwalk (This creature can't be blocked as long as defending player controls a Forest.)

If an opponent had two or more creatures enter the battlefield under their control this turn, you may pay rather than pay this spell's mana cost.

Return two target creatures to their owners' hands.

: Exile target instant or sorcery card from a graveyard. Roll a d20. Activate only as a sorcery.

1–9 | Copy that card. You may cast the copy.

10–19 | Copy that card. You may cast the copy by paying rather than paying its mana cost.

20 | Copy each card exiled with Wizard's Spellbook. You may cast any number of the copies without paying their mana costs.

Casualty 2 (As you cast this spell, you may sacrifice a creature with power 2 or greater. When you do, copy this spell.)

Each opponent exiles the top card of their library. You may cast spells from among those cards this turn. If you cast a spell this way, pay life equal to that spell's mana value rather than pay its mana cost.