Voltaic Key

Clockwork Beast

Clockwork Beast enters the battlefield with seven +1/+0 counters on it.
At end of combat, if Clockwork Beast attacked or blocked this combat, remove a +1/+0 counter from it.
{X}, {T}: Put up to X +1/+0 counters on Clockwork Beast. This ability can't cause the total number of +1/+0 counters on Clockwork Beast to be greater than seven. Activate only during your upkeep.

Black Lotus

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

Demonic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Mox Sapphire

Swamp

Time Vault

Time Vault enters the battlefield tapped.
Time Vault doesn't untap during your untap step.
If you would begin your turn while Time Vault is tapped, you may skip that turn instead. If you do, untap Time Vault.
{T}: Take an extra turn after this one.

Tolarian Academy

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

Monkey Cage

When a creature enters the battlefield, sacrifice Monkey Cage and create X 2/2 green Monkey creature tokens, where X is that creature's mana value.

Island

Counterspell

Twiddle

You may tap or untap target artifact, creature, or land.

Sol Ring

Underground Sea

Library of Alexandria

{T}: Add {C}.
{T}: Draw a card. Activate only if you have exactly seven cards in hand.

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Timetwister

Each player shuffles their hand and graveyard into their library, then draws seven cards. (Then put Timetwister into its owner's graveyard.)