Boxing Ring kills my creatures that should survive the fight

I summoned [[Roaming Throne]] to fight [[Atla Palani, Nest Tender]] with [[Boxing Ring]]. I selected the effect of Boxing Ring and when it started to resolve, my Roaming Throne was marked with 2 Damage while Atla Palani was still alive. When it fully resolved, both creatures suddenly died. Atla Palani didn't have any buffs or death touch or anything.