Combo Magosi, the Waterveil +Rings of Brighthearth +Deserted Temple + Magic: the Gathering MTG

Activate Deserted Temple's ability to untap Magosi Respond to the ability by paying two mana and activating Rings of Brighthearth, copy Deserted Temple's ability, target Magosi again. Let the copy resolve, untap Magosi, and respond to the second ability by tapping it to put an Eon counter on Magosi. Untap Magosi and activate its ability to take an extra turn. Respond to the ability by copying it with Rings of Brighthearth. Repeat the process on the next turn for infinite turns.

Legallity