A couple of weeks ago I solo'd this delve, after assistance on 2H tanking I garnered here. Thanks.

.
I'm a natural DW & bow st NB Imp, so I was quite proud of this achievement, & remember the fight clearly.
Last night I returned under the Corrupted Stone quest still solo as I have no friends (my character isn't called Assassin Loner by mistake

), and not only struggled a lot more with the trash, I also couldn't exterminate the boss in the side room, and in no way could I even get Izrunath to 75% health, much less release his two mates, his two snakes, or kill him.
So please riddle me this, is it possible the game strengthened the delve under the quest scenario?
I'm on XBox EU so IC hasn't dropped yet for us.
I've not altered any skills/CP points, armour, etc. I've never had any Cyro buff as my home campaign is stuck in an AD buff without AP (I don't much like Pvp) to change it, etc...but last night Izrunath was dumping heavy attacks (without annimation) for 11,500 once every 5 moves, the other 4 light attacks being 4,000 each, rinse & repeat, so even avoiding his Ult drops, I couldn't scratch him with a Bow, & Rally couldn't keep me in the fight for more than perhaps 90 seconds as once I ran out of stamina from dodge-rolling I couldn't escape his claws out of the floor thing with any longer either which also then hit for about 5,000 (I assume over time).
I'm confused if anyone can shed light?
If I can't do it, I can't do it, it's not called a group delve by mistake I accept, but the change is tangible yet I would've imagined impossible...
II Swindy II
Australian on Xbox NA (ex EU)