Rings of Brighthearth + Seeker of Skybreak + Bloom Tender

Rings of Brighthearth

Seeker of Skybreak

Bloom Tender

How it works

1. Activate Bloom Tender by tapping it, adding at least three mana of different colors.
2. Activate Seeker of Skybreak by tapping it.
3. Rings of Brighthearth triggers, allowing you to pay 2 to copy Seeker of Skybreak's ability and choose a new target for the copy.
4. Resolve both copies of Seeker of Skybreak's ability, untapping Seeker of Skybreak and Bloom Tender.
5. Repeat.
6. Once you have infinite mana, you may untap any creature instead of Bloom Tender in step 4.