Since the Roarmulus Twins are immune to shard bombs and part of the thing about the game is that you can more or less beat anything with anything, how about we fix this up? That's right! Yes! You are indeed correct!
Let's make the Twins immune to every weapon in the game!
And let's make vials the only method of killing them!
Krakob walks away and reads a book about monks killing eachother and stuff to his stuffed snipe on his hat.
+1