Does Tideturner cause you to lose control of a battlefield mid-resolution when swapping units, potentially allowing you to contest or score?

Ruling: You do not lose control of a battlefield during Tideturner's resolution. Control is only checked during cleanups, which occur after the entire effect resolves, not in the middle of it.

Sequence:

• Tideturner's effect begins resolving as one complete action
• Both unit moves occur as part of this single resolution (though not truly simultaneously, as game actions cannot be simultaneous)
• After the entire effect finishes resolving, cleanup occurs
• Control is checked during this cleanup, not during the resolution

Nuances:

• Rule 181.4.c states control is lost "immediately" when you have no units at a battlefield, which initially suggested mid-resolution control loss
• However, rule 322.4 (which handles control during cleanups) is more specific and takes precedence
• Rule 151.3.a states nothing can be addressed during resolution, including things caused by execution
• The moves within Tideturner are part of one game action; the move is not "complete" until the ability finishes resolving
• This only matters in edge cases where another unit at the battlefield is removed in response (via Gust, Retreat, etc.) before Tideturner resolves