Weaver of Harmony does not have summoning sickness.
You control a creature other than Weaver of Harmony that can attack this turn and that cannot be blocked by an opponent.
You control at least two mana-producing lands except Weaver of Harmony, one of which must be a Forest.
Steps
Deal combat damage to an opponent using a creature other than Weaver of Harmony, triggering Nature's Will.
Holding priority, activate all mana-producing lands you control except Weaver of Harmony by tapping them, adding at least ({1} magic symbol) ({G} magic symbol) .
Activate Weaver of Harmony by paying ({G} magic symbol) and tapping it, copying Nature's Will's trigger.
Resolve the copy of Nature's Will's trigger, untapping all lands you control and tapping all lands the defending player controls.
Repeat from step 2.
Results
Infinite mana lands you control can produce.
Infinite mana nontoken creatures you control can produce.