Infinite combat phasesInfinite mana creatures you control can produceInfinite untap of creatures you controlInfinite mana basic lands you control can produce
How it works
Cast Sylvan Offering by paying 5, causing you and an opponent to create a 5/5 Treefolk creature token and five 1/1 Elf Warrior creature tokens.
Activate Earthcraft by tapping the Treefolk token, untapping a basic Mountain you control.
Activate the Mountain by tapping it, adding .
Repeat from step 2 five additional times, tapping the Elf Warrior tokens instead.
Activate Aggravated Assault by paying 3, untapping all creatures you control and giving you an extra combat and main phase after this one.