AST should have one default and one toggled sect

[ForteNightshade]

My apologies it wasn’t empty wave, it was the post adds raidwide damage that killed the whm, they had 103k total hp roughly.

You should still be able to live that. Maybe you'll need a tank CD there but I'm pretty certain it doesn't one-shot if the White Mage with that ilvl. It could be their healing cast went out at the same time, and because XIV registers damage first, they were snapshot with less HP than what their HP bar actually showed.