Activate Ashnod's Altar by sacrificing Patron of the Arts, adding ({C} magic symbol) ({C} magic symbol) .
When Patron of the Arts dies, it and Rakdos trigger.
Resolve the Patron of the Arts trigger, creating a Treasure token.
Activate the Treasure by tapping and sacrificing it, adding ({B} magic symbol) .
Holding priority, activate Haunted Crossroads by paying ({B} magic symbol) , putting Patron of the Arts from your graveyard onto the top of your library.
Resolve the Rakdos trigger, exiling three cards from the top of your library, including Patron of the Arts, with the ability to cast it until your next turn.
Cast Patron of the Arts from exile by paying ({3} magic symbol) .
When Patron of the Arts enters the battlefield, it triggers, creating a Treasure token.
Activate the Treasure by tapping and sacrificing it, adding ({1} magic symbol) .
Repeat.
Results
Infinite LTB.
Infinite ETB.
Infinite sacrifice triggers.
Infinite death triggers.
Infinite storm count.
Exile your library with the ability to play the exiled cards until your next turn.