unable to damage worm boss

[delta8768]

i am unable to do any damage at all to the lvl 10 worm boss, every attack i hit him with just says
"immune", and killing all the little worms does nothing to his health either. Am i just missing somthing somewhere, any help here would be nice.

[Warzonic]

Hmmmm, take a good look at all the little worms... One of them maybe look like that little "worm" you attack to start the fight? I'll spoil it if you want to. But I feel thats a good enough hint.

[😒]

Kill mobs till you hit the tail, he falls, then "enrage" and smack away. Probably takes 3 round or so.