The mechanic is a bit forgivable, I run it with my friends and we kinda BS through it, the sin failed to stealth so they got knockback and didn't get rootedor heaven breach, but we somehow survived by BM HM block, marker job is to run away from boss because after the Heaven breach you will get rooted and die from red attack.
As for sanctum, I put middle stage so i can daze him just in case they burned out their tab escape before we get suck in