Midnight Clock

{T}: Add {U}.
{2}{U}: Put an hour counter on this artifact.
At the beginning of each upkeep, put an hour counter on this artifact.
When the twelfth hour counter is put on this artifact, shuffle your hand and graveyard into your library, then draw seven cards. Exile this artifact.

Time Bomb

At the beginning of your upkeep, put a time counter on this artifact.
{1}, {T}, Sacrifice this artifact: This artifact deals damage equal to the number of time counters on it to each creature and each player.

Rusko, Clockmaker

When Rusko, Clockmaker enters the battlefield, conjure a card named Midnight Clock onto the battlefield.
Whenever you cast a noncreature spell, put an hour counter on each permanent you control named Midnight Clock. Each opponent loses 1 life and you gain 1 life.

Telling Time

Look at the top three cards of your library. Put one of those cards into your hand, one on top of your library, and one on the bottom of your library.

Nuclear Fallout

Each creature gets twice -X/-X until end of turn. Each player gets X rad counters.

Clockwork Steed

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

Clockwork Swarm

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

Foundry Inspector

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

Blood Clock

At the beginning of each player's upkeep, that player returns a permanent they control to its owner's hand unless they pay 2 life.