only thought I had for some new mechanic was the boss eats whoever is highest on arrgo, boss room unlocks & then chases the team around using AoE's only till he finally spits them out when they make it back to the 1st bosses room or they do enouf dmg to get themself out (which could just be the thing that makes him spit them out later), even have it so it happens at a random time after he hits below 75% but before 25% to add the fear of "when's it gona happen" to the party, could even make the boss invinible/untargetable during the run too