I truly hope they buff BRD...

[BloodRubyXII]

I already tried melee LB with both Trick Attack and Shadow Fang active and it still did the usual 10K damage.

I didn't try it with Blood for Blood, but I suppose it would be easy enough to test.

EDIT: Nope. Blood for Blood doesn't work either, so I guess neither player-applied damage buffs nor vulnerability debuffs influence it.

It's the damage taken aspect of BFB, not the damage dealt, I'm kinda surprised I had to clarify this because Casters don't have BFB. Melee LB is affected by culling but we're discussing caster LB in any case.

Dunno how vuln/damage up stacking is calculated or how applicable it is, whether it has DR etc though, being honest I've never really paid attention to it, if you get LBed by a melee and you're not a tank, a range on full hp, or a healer that's reasonably topped off you're going to die regardless anyway.

[KageTokage]

I'm just dumb, though I think most people already think that at this point.

I guess the rule is self-induced/environmental vulnerabilities such as PLD's Cover/Blood for Blood/culling time can make LBs deal more damage, but hostile ones applied by other players won't.