Can Janna be played to save a unit from Void Seeker when attacking at a battlefield with Azir?

Ruling: Janna cannot be played to save a unit from Void Seeker when you are attacking at a battlefield. Janna's trigger specifies "here" and she can only be played at your base or battlefields you control, but you definitionally don't control a battlefield where you are the attacker.

Nuances:

• Even if you react to Void Seeker with Janna, it won't do anything unless the unit already has damage marked on them
• You would need to let Void Seeker resolve first and then play Janna for the effect to work (in scenarios where Janna can be played)
• The "here" restriction on Janna's trigger prevents her from being used at battlefields where you are attacking