Commence the Endgame

Mana cost: {4}{U}{U}
Type: Instant
Set: Aetherdrift Commander #38 (rare)
Price: $0.29 USD

This spell can't be countered.
Draw two cards, then amass Zombies X, where X is the number of cards in your hand. (Put X +1/+1 counters on an Army you control. It's also a Zombie. If you don't control an Army, create a 0/0 black Zombie Army creature token first.)

Commence the Endgame has 4 printings, first in War of the Spark (2019). EDHREC ranks it #8,483 among Commander cards. It appears most in Temmet, Naktamun's Will decks (3,028 on EDHREC). 1 public deck on TCG runs it. It has 8 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 Commence the Endgame

Eternal Might - Aetherdrift Commander, led by Temmet, Naktamun's Will

Commanders that run Commence the Endgame most

Deck counts from EDHREC.

Temmet, Naktamun's Will: 3,028 decks
Saruman, the White Hand: 2,558 decks
Sauron, the Dark Lord: 2,532 decks
Nicol Bolas, the Ravager // Nicol Bolas, the Arisen: 1,146 decks
Grandmother Goby: 273 decks
Ojer Pakpatiq, Deepest Epoch // Temple of Cyclical Time: 245 decks
Nicol Bolas: 137 decks
Kairi, the Swirling Sky: 76 decks

Often played with Commence the Endgame

Cards that show up in the same decks on EDHREC.

Rulings

2019-05-03: A spell or ability that counters spells can still target Commence the Endgame. When that spell or ability resolves, Commence the Endgame won't be countered, but any additional effects of that spell or ability will still happen.
2019-05-03: You draw two cards and amass X all while Commence the Endgame is resolving. Nothing can happen between the two, and no player may choose to take actions.
2023-06-16: To amass Zombies N, if you don't control an Army creature, create a 0/0 black Zombie Army creature token. Then you choose an Army creature you control and put N +1/+1 counters on it. If that Army isn't already a Zombie, it becomes a Zombie in addition to its other types.
2023-06-16: Amass Orcs works the same way, except you create a 0/0 black Orc Army creature token if you don't control an Army. If the Army creature you chose isn't already an Orc, it becomes an Orc in addition to its other types. By combining cards with amass Orcs and amass Zombies, you can end up with an Orc Zombie Army.
2023-06-16: Amass abilities are now written as "amass [subtype] N." Previous cards with amass have received errata to say "amass Zombies N."
2023-06-16: If you don't control an Army, the Zombie Army token you create enters the battlefield as a 0/0 creature before receiving counters. Any abilities that trigger when a creature with a certain power enters the battlefield, such as that of Mentor of the Meek, will see the token enter as a 0/0 creature before it gets +1/+1 counters.
2023-06-16: Some cards refer to the "amassed Army." That means the Army creature you chose to receive counters, even if no counters were placed on it for some reason.
2023-06-16: In the rare case that you control multiple Army creatures (perhaps because you played a creature with changeling) while you amass Zombies, you choose which of your Army creatures to put the +1/+1 counters on. If that creature isn't a Zombie, it becomes a Zombie in addition to its other types.