Thieving Amalgam

Mana cost: {5}{B}{B}
Type: Creature — Ape Snake
Power / toughness: 6 / 7
Set: Outlaws of Thunder Junction Commander #150 (rare)
Price: $1.08 USD

At the beginning of each opponent's upkeep, you manifest the top card of that player's library. (Put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)
Whenever a creature you control but don't own dies, its owner loses 2 life and you gain 2 life.

Thieving Amalgam has 2 printings, first in Commander 2019 (2019). EDHREC ranks it #5,573 among Commander cards. It appears most in Kadena, Slinking Sorcerer decks (4,487 on EDHREC). 2 public decks on TCG run it. It has 5 official rulings.

Legality

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

Public decks that run Thieving Amalgam

Faceless Menace - Commander 2019, led by Kadena, Slinking Sorcerer
Grand Larceny - Outlaws of Thunder Junction Commander, led by Gonti, Canny Acquisitor

Commanders that run Thieving Amalgam most

Deck counts from EDHREC.

Often played with Thieving Amalgam

Cards that show up in the same decks on EDHREC.

Rulings

2019-08-23: Your opponents can't look at the card they own that you manifested.
2019-08-23: If a creature you control but don't own dies at the same time that its owner leaves the game, Thieving Amalgam's last ability triggers. No player loses 2 life, but you gain 2 life.
2019-08-23: In the Commander variant, you can produce mana that isn't of your commander's color identity if an effect lets you produce mana of that color or mana of any color, even though those symbols can't appear on cards in your deck. You may be able to turn a manifested creature card face up this way if it's not the same colors as your commander.
2019-08-23: In a multiplayer game, if a player leaves the game, all cards that player owns leave as well. If you leave the game, the creatures you manifested with Thieving Amalgam's triggered ability are exiled.
2019-08-23: If a creature you control but don't own dies at the same time that your life total becomes 0 or less, you lose the game before Thieving Amalgam's last ability can save you.