Midnight Clock

Mana cost: {2}{U}
Type: Artifact
Set: Throne of Eldraine Promos #54s (rare)

{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.

Midnight Clock has 13 printings, first in Throne of Eldraine (2019). EDHREC ranks it #661 among Commander cards. It appears most in Obeka, Splitter of Seconds decks (4,929 on EDHREC). 7 public decks on TCG run it. It has 4 official rulings.

Legality

commander: legal
legacy: legal
vintage: legal
pauper: not legal
modern: legal
pioneer: legal
standard: not legal
brawl: legal

Public decks that run Midnight Clock

Bedecked Brokers - New Capenna Commander, led by Perrie, the Pulverizer
Creative Energy - Modern Horizons 3 Commander, led by Satya, Aetherflux Genius
Draconic Dissent - Commander Legends: Battle for Baldur's Gate, led by Firkraag, Cunning Instigator
Fae Dominion - Wilds of Eldraine Commander, led by Tegwyll, Duke of Splendor
Living Energy - Aetherdrift Commander, led by Saheeli, Radiant Creator
Quick Draw - Outlaws of Thunder Junction Commander, led by Stella Lee, Wild Card
Spirit Squadron - Crimson Vow Commander, led by Millicent, Restless Revenant

Commanders that run Midnight Clock most

Deck counts from EDHREC.

Often played with Midnight Clock

Cards that show up in the same decks on EDHREC.

Rulings

2019-10-04: Midnight Clock's first triggered ability triggers at the beginning of each upkeep, not just your upkeep. In a Two-Headed Giant game, an ability that triggers at the beginning of each upkeep rather than each player's upkeep triggers only once during each team's upkeep.
2019-10-04: You can activate Midnight Clock's mana ability to pay the cost of its second ability.
2019-10-04: Midnight Clock's last ability triggers after one or more counters are put onto it if it had fewer than twelve counters on it before those counters were put on it and it has twelve or more counters on it after.
2019-10-04: If Midnight Clock leaves the battlefield while its last ability is on the stack, it won't be exiled.