Empress summons before half HP.

This is correct. You hit her when she's on damage and the players affected can be anyone and any number on the map (probably a cap of 6 people max but doesn't really matter)

i haven't had the chance to experiment (mainly because nobody wants to die) but i think it's 1 attack = 1 death, otherwise impale and such would be horrible.

For us, it always seemed to be the bishops that got hit with the 50k
(many lulz were had)

don't remind me, in my experience first to get reflected is the darned mages. and if there's a bishop, like 150% chance of it dying first.

is there any other boss with a special "damage reflect" skill? i know mu gong has 2 reflects instead of 1, but are there any others?