If Hidden Blade targets a unit at one battlefield, but the unit moves to a different battlefield in response (via Tideturner), does Hidden Blade still kill the unit?

Ruling: Yes, Hidden Blade still kills the unit even if it moves to a different battlefield after being targeted. When targeting Hidden Blade, you only declare the unit (not the specific battlefield), as long as that unit is at a battlefield when targeted.

Sequence:

• Hidden Blade is played targeting unit A at battlefield 1
• In response, Tideturner moves unit A from battlefield 1 to battlefield 2
• Hidden Blade resolves and kills unit A at its new location (battlefield 2)
• Hidden Blade's controller draws 2 cards

Nuances:

• The targeting requirement "a unit at a battlefield" only requires declaring a unit that is currently at any battlefield, not a specific battlefield
• If the target becomes illegal upon resolution (e.g., the unit is no longer at any battlefield), Hidden Blade does not draw cards because the instruction references the target's controller