Quote Originally Posted by Estellios View Post
This isn't true. You start with 1 bar in a 4 person party and 2 bars in an 8 person party. The extra bar gets added on as soon as you engage the final boss of the dungeon. For primals I don't remember if you start with 2 and get a 3rd upon engaging or just start with 3, but you have 3 bars for those.
Primals you start with 2 and build up to 3 as soon as you enter battle but any progress on LB bar is wiped as soon as you engage the primal. I've never seen a boss that has a last bar appear at lower HP.