This started out as me just being upset and turned into a puzzle I couldn't leave unsolved because it would mean admitting defeat... but I finally figured it out! As it turns out I had to look at someone else's log of the same fight because my log was missing random bits and pieces I guess due to being too far away from the other parties? I figured ACT would still pick it up but I guess not.

For anyone doing FT if you ever need to figure out who greeded holy lance on a wipe or something and you have a few logs to check, here's how:

>Open magitaur log
>Leave it on "Analyze"
>Click "events" below
>Click "Damage taken"
>Right below damage taken click the dropdown for "All Abilities"
>Select "Holy IV" (This is the party stack damage)
>now read the table below, you will see "Magitaur # prepares Holy IV on <name>"
>These different numbered Magitaur sources are the 3 different stack markers going off
>in my case there was a 7, 1, and 2 but those numbers seem random per pull
>if you only see 2 numbers then your log is scuffed and you need someone else's log for their pov
>they swap squares randomly for each party stack so don't fixate one just one number
>instead just check the timeline for the same moment everyone died
>After all the "Magitaur # prepares Holy IV on <name>" lines you'll see it change to "Magitaur # Holy IV <name>" and the first 3 lines will be 3 different magitaur numbers
>these 3 are your party stack people, from there you have to use your roster or the replay option to see who was on what square to narrow down the culprit

I know someone said "the first 3 people to take damage" earlier but when I used the timeline instead of events I found some cases where someone not targeted by the stack still took damage at the exact same moment, probably because they were stacked right on them and the damage in this game radiates outward from the source so it'd make sense.

I corroborated these findings with other players and my video replay and it was accurate.