Cast Traveling Plague by paying 3, attaching it to another creature you control.
When Traveling Plague enters, Ghostly Dancers triggers, creating a creature token.
Activate Altar of Dementia by sacrificing the creature Traveling Plague is attached to.
When the creature dies, Traveling Plague triggers, returning itself from your graveyard to the battlefield attached to the token created in step 2.
When Traveling Plague enters, Ghostly Dancers triggers, creating a creature token.
Resolve the Altar of Dementia ability.
Repeat from step 3.
This clever recursive loop turns a creeping curse into a mill machine by exploiting the built-in self-recursion of Traveling Plague. Whenever you sacrifice the enchanted creature to Altar of Dementia, the Aura's triggered ability pulls it right back from the graveyard and attaches it to the new target. Meanwhile, Ghostly Dancers acts as the engine's catalyst; its *Eerie* ability notices Traveling Plague constantly entering the battlefield and churns out a steady stream of 3/1 white Spirit creature tokens to keep the sacrifice fodder flowing.