Oh, and repeatedly press Q and left mouse like hell if you get caught in the cobweb before it consumes you.
(Igni and Aard is useful)
Cut off the cobweb and run like hell. That's all.

Note: If you're Level 3 like me, you REALLY MUST cheat out on this one.

Stock up on Grapeshot. The best one.
Hide behind the pillar next to where that monster was, and now it's time for "cheating."
Select bomb in quick menu, then throw one to the wall far away from you.
Now, you must take serious attention to that distance meter.
If it's less than 15, throw a bomb to that far-away wall, then hide. One step late, and you'll get 4,479 damage. (It'll result in health rapidly falling down to about -3999, AKA TOTALLY DEAD.)
If it's about 24ft, it's safe, Throw shitload of bomb to that bastard, then hide.
Repeat this about 25~58 times and the quest will be almost over.
(It depends on the damage of the bomb you're using. Always pick the highest one!)

You might REALLY want to use Trainer and add bomb to your inventory.

Phew. It's over. I died 3 times.