Instead of letting the boss' attention go back to Thomas, who was ostensibly the group's main tank, Karl kept the attention on himself to test the changes to his body.
With Cara, they could nullify the strongest of the Boss attacks, but the ones that were hitting Karl were still enough to take down his barrier in a single strike.
He wasn't in a hurry to bring them back up, though. He had to see what would happen if one actually hit him, with [Void Body], [Impenetrable Bulwark], and his new constitution.
The first strike that hit without a barrier up slid Karl back by over a metre, but only left a thin gouge in his armour spell, and what was likely to be a nasty bruise underneath.
That was a pleasant change, those hits were taking most of his effort to keep everyone protected through last time. If Karl had to guess, he would say that he was very close to on par with the Dungeon Boss as far as durability went, but with faster regeneration.
