Canker Abomination enters the battlefield, it triggers, putting a number of -1/-1 counters on it equal to the number of creatures an opponent controls.
Canker Abomination dies as a state-based action due to having 0 or less toughness, triggering its undying ability, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
Repeat from step 2.
Results
Infinite LTB.
Infinite ETB.
Infinite death triggers.
Metadata
In 23 decks according to EDHREC.
Bracket Tag
This combo has been estimated to be Exhibition (Bracket 1+).