Putrid Goblin does not have a -1/-1 counter on it.
Mana Needed
({1} magic symbol) ({R} magic symbol) available.
Steps
Cast
First Day of Class by paying ({1} magic symbol) ({R} magic symbol) , causing all creatures that enter the battlefield under your control this turn to get an additional +1/+1 counter put on it.
Activate
Altar of Dementia by sacrificing
Putrid Goblin.
Putrid Goblin's persist ability triggers, returning itself from your graveyard to the battlefield with a -1/-1 counter on it.
Putrid Goblin enters the battlefield, triggering
First Day of Class, putting a +1/+1 counter on
Putrid Goblin.
Resolve the
Altar of Dementia ability from step 2, causing target player to mill cards equal to
Putrid Goblin's power.
Repeat from step 2.
Results
Infinite death triggers.
Infinite creature ETB.
Infinite creature LTB.
Infinite mill.
Infinite creature sacrifice triggers.
Infinite self-mill.
Metadata
Bracket tag
ExhibitionBracket 1+
For any deck
1
2
3
4
5
1 · Exhibition5 · cEDH
Bracket tags are estimated from the cards and results of each combo, as a guideline rather than a strict classification.