Miirym, Sentinel Wyrm | Worldgorger Dragon

Cards

Miirym on the battlefield.
Worldgorger Dragon in hand.
({3} magic symbol) ({R} magic symbol) ({R} magic symbol) ({R} magic symbol) available.

Cast
Worldgorger Dragon by paying ({3} magic symbol) ({R} magic symbol) ({R} magic symbol) ({R} magic symbol) .
Worldgorger Dragon enters the battlefield, triggering its first ability and
Miirym.
Holding priority, you may activate all mana-producing permanents you control by tapping them, adding at least ({1} magic symbol) .
Resolve the
Miirym trigger, creating a token copy of
Worldgorger Dragon.
The
Worldgorger Dragon token enters the battlefield, exiling all other permanents you control.
The nontoken
Worldgorger Dragon's second ability triggers, returning nothing to the battlefield.
Resolve the nontoken
Worldgorger Dragon's first ability from step 2, exiling all other permanents you control.
The token
Worldgorger Dragon leaves the battlefield, returning all cards exiled with it to the battlefield from exile.
Repeat from step 2 in an infinite loop, drawing the game unless you can use the infinite mana to win the game or remove a combo piece at instant speed.