Titania, Protector of Argoth + Command Beacon + Food Chain

Steps

1. Activate Command Beacon's second ability by tapping and sacrificing it.
2. Titania's second ability triggers, creating a 5/3 Elemental creature token.
3. Activate Food Chain by exiling Titania, adding six {G} that can only be spent to cast creature spells.
4. Choose to have Titania put into the command zone from your graveyard.
5. Resolve the Command Beacon ability from step 1, putting Titania from the command zone into your hand.
6. Cast Titania by paying {3}{G}{G}.
7. Titania enters the battlefield, returning Command Beacon from your graveyard to the battlefield.
8. Repeat.