When Mistbind Clique enters the battlefield, its champion ability and Molten Echoes triggers.
Resolve the Molten Echoes trigger, creating a token copy of Mistbind Clique with haste.
When the Mistbind Clique token enters the battlefiled, its champion ability triggers, exiling the nontoken Mistbind Clique until the token Mistbind Clique leaves the battlefield.
Resolve the champion ability from step 2, exiling the token Mistbind Clique.
The token Mistbind Clique leaves the battlefield, returning the nontoken Mistbind Clique from exile to the battlefield.
Repeat from step 2.
By naming Faerie as the creature type for Molten Echoes, you set the stage for Mistbind Clique to enter the battlefield and trigger a continuous loop of duplication and resource denial. When you cast Mistbind Clique, its champion ability and Molten Echoes trigger simultaneously, allowing the token copy to enter, trigger its own champion ability to exile the original, and immediately lock down an opponent's lands. Because exiling the original Mistbind Clique causes the token to vanish and return the original to the battlefield, you can repeat this process endlessly to generate infinite entrance and departure triggers.