i am a level 35 fire and when i got to kensington park i had a level 45 myth help me with the first boss and we got smited :(. anyways it is too hard the first guy wow. i started thinking to myself what is the last boss . but yea its too hard.
This dungeon is meant to be a challenge and usually is done by higher level wizards who are bored with the game.
Thankfully it does remove it self from the book once you enter it if you accidentally take it and do not realize it isn't needed to continue on in the game.
Many instances are in the Spiral that are now optional that don't come out of your book if you do not complete it so head up for the following:
Level 50's - BriskBreeze, MarleyBone Warehouse, Level 60's, Helephant Tower and actually WaterWorks is optional unless you want your level 60 gear.
I learned the hard way after taking them they were optional and actually when I joined the game the Warehouse was not - ugh.