When playing Tideturner from hidden at one battlefield during a showdown, can it target and switch with units at a different battlefield?

Ruling: Yes, Tideturner can target units at any battlefield when played from hidden. This is an exception to how hidden cards normally work.

Sequence:

• Play Tideturner from hidden at a battlefield
• Tideturner enters play at that battlefield
• Its "when you play" triggered ability goes on the Chain
• The ability can now target any friendly unit at any battlefield because the targeting happens after the unit is played, not during the playing of the unit

Nuances:

• This works differently than cards like Blastcone Fae or Teemo, which must target units at the same battlefield they were hidden at, even though the rules as written would suggest they should work the same way as Tideturner
• The distinction is that Tideturner's targeting happens as part of a triggered ability after it's played, while other cards require choosing targets as a condition of playing them
• The rules as written support Tideturner working this way, but other hidden cards are intended to work differently and will be clarified in future rules updates