I’m sure there is something this boss does apart from dying fast, but I havent found it yet.
Cragmaw the Infested
Go away from the direction he’s facing when he’s charging. Go step on red things on ground so it doesnt spawn little adds that will stack a nasty dot on you.
He will spawn green shrooms around him. When you have a big arrow above your head, go stand near those shrooms (but not IN it). If you’re the tank, make him face a big chunk of shrooms and bring him quite close to it so when he cast shockwave he will clean those shrooms. If you clean enough shrooms you wont die when he makes them explode.
He is immune to damage but that doesnt mean you dont have to do damage to him. Just dps him. Don’t stand on grey poo on the ground. When you or someone in your party has a big yellow circle around him, go stand in it. Use the big yellow circle if its around you to cleanse grey poo on the ground (dont stand inside it though, just next to it). When little blood adds spawn, the big titan helping you will stun one. Go kill the other one.