Molten Echoes on the battlefield (with "Elemental" chosen).
({6} magic symbol) ({U} magic symbol) available.
Steps
Cast Supreme Exemplar by paying its mana cost.
When Supreme Exemplar enters the battlefield, its champion ability and Molten Echoes triggers.
Resolve the Molten Echoes trigger, creating a token copy of Supreme Exemplar with haste.
When the Supreme Exemplar token enters the battlefiled, its champion ability triggers, exiling the nontoken Supreme Exemplar until the token Supreme Exemplar leaves the battlefield.
Resolve the champion ability from step 2, exiling the token Supreme Exemplar.
The token Supreme Exemplar leaves the battlefield, returning the nontoken Supreme Exemplar from exile to the battlefield.