Does moving a unit to an opponent-controlled battlefield with Zenith Blade count as attacking, and what happens in combat when the attacker has less total might than defenders but one defender is stunned?

Ruling: Moving Leona to an opponent-controlled battlefield with Zenith Blade does count as attacking. In the combat scenario described, if both sides have units remaining after combat resolves, the attackers are sent home via retreat.

Nuances:

• A unit is considered attacking if it contests a battlefield controlled by an opponent, regardless of whether it arrived via normal move or card effect like Zenith Blade
• The retreat rule applies when both sides have units left at the end of combat