Activate Altar of Dementia by sacrificing Kitchen Finks.
When Kitchen Finks dies, its persist ability triggers, returning Kitchen Finks from your graveyard to the battlefield with a -1/-1 counter on it.
When Kitchen Finks enters the battlefield, it triggers, causing you to gain 2 life.
Spider-Man triggers, putting a +1/+1 counter on Kitchen Finks.
Resolve the Altar of Dementia ability.
Repeat.
This ingenious loop is anchored by Kitchen Finks, whose persist ability normally lets it return to the battlefield just once after dying with a -1/-1 counter. However, Altar of Dementia provides the necessary sacrifice outlet to send it to the graveyard repeatedly, while simultaneously turning all those iterations into an infinite mill stream for your opponents. The real magic happens because Spider-Man, Peter Parker watches you gain life from the entering Finks and counters that pesky -1/-1 counter by placing a +1/+1 counter on it. Since +1/+1 and -1/-1 counters neutralize each other as a state-based action, Kitchen Finks is left completely clean and ready to persist all over again.