Possible Parsing Bug on Xavius (EN Normal)

Last night on one of the Xavius pulls, our fully topped off tank took ~3.8 million damage from a single ability that I can’t identify and I’m not sure that WL is parsing it either.

This is a 30 second window from that pull. The tank, Pisomojado, dies at 2:46, after taking a huge hit to his HP at 2:45.


When I look at his damage taken, it shows a single tick of Tainted Discharge.


Is there another ability that WL is not parsing or did RNGesus punish my tank with no apparent reason?