Megaton's Fate + Dualcaster Mage + Deadeye Navigator + Artifact that is Indestructible

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How it works

Cast Megaton's Fate by paying , targeting the indestructible artifact.
Holding priority, activate Dualcaster Mage by paying , blinking it.
When Dualcaster Mage enters the battlefield, it and Deadeye Navigator's soulbond ability trigger.
Resolve the Deadeye Navigator trigger, repairing it and Dualcaster Mage.
Resolve the Dualcaster Mage trigger, copying Megaton's Fate, with the copy targeting the indestructible artifact.
Resolve the copy of Megaton's Fate, failing to destroy the artifact due to it being indestructible, and creating four Treasure tokens.
Activate two Treasure tokens by tapping and sacrificing them, adding .
Repeat from step 2.

In which brackets is this combo allowed, per Spellbook's Exhibition tier?

1–2 · Exhibition & Core

Allowed in this bracket.

3 · Upgraded

Allowed in this bracket.

4–5 · Optimized & cEDH

All combos are allowed.