Mox Diamond

If Mox Diamond would enter, you may discard a land card instead. If you do, put Mox Diamond onto the battlefield. If you don't, put it into its owner's graveyard.
{T}: Add one mana of any color.

Power Sink

Counter target spell unless its controller pays {X}. If that player doesn't, they tap all lands with mana abilities they control and lose all unspent mana.

Mind Over Matter

Discard a card: You may tap or untap target artifact, creature, or land.

Voltaic Key

Stroke of Genius

Intuition

Search your library for three cards and reveal them. Target opponent chooses one. Put that card into your hand and the rest into your graveyard. Then shuffle.

Volcanic Island

City of Brass

Whenever City of Brass becomes tapped, it deals 1 damage to you.
{T}: Add one mana of any color.

Time Spiral

Exile Time Spiral. Each player shuffles their hand and graveyard into their library, then draws seven cards. You untap up to six lands.

Lotus Petal

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

Tundra

Scroll Rack

{1}, {T}: Exile any number of cards from your hand face down. Put that many cards from the top of your library into your hand. Then look at the exiled cards and put them on top of your library in any order.

Abeyance

Until end of turn, target player can't cast instant or sorcery spells, and that player can't activate abilities that aren't mana abilities.
Draw a card.

Tolarian Academy

{T}: Add {U} for each artifact you control.

Mana Vault

Mana Vault doesn't untap during your untap step.
At the beginning of your upkeep, you may pay {4}. If you do, untap Mana Vault.
At the beginning of your draw step, if Mana Vault is tapped, it deals 1 damage to you.
{T}: Add {C}{C}{C}.

Windfall

Each player discards their hand, then draws cards equal to the greatest number of cards a player discarded this way.