I have noticed that there is a super hard dungeon for each world here are some i have found out: wizard citysuken city how is a level 10-20 ment to do that even with friends!!! KROK (this i found hardest when its not ment to be :x :x) tomb of the buguleir i think in well of spirits krokopatra is hard to solo by yourself with two people its easy she has 1100 health which is to the average wizard because the first thing 3000 health with good helpers not even the final boss of marleybone is better even with the boss helpers and getting there big ben diffulcty for the average marlybone wizard is 10/10 and the difulcty for the average marlybone wizard for the tomb is 10000/10
marleybone: ken park (personly i found this easy but it is ment to be really hard to other wizards) mooshu and DS and GH i cant find any if you know some really hard dungeons for the average wizard in the world please tell me !!!! PLEASE NOTE that briskbreeze and warehouse preview quest dosen't cound becuase there both for grandmasters (not many non grands do the warehouse quest PLEASE COMMENT or ill be really BYE gl wizards :P
The three instances you mentioned are all optional and don't have to be done to continue in the game. They're "bonus dungeons". You're not expected to be able to do those alone at the level you'd be at while doing the storyline quests in each area.
:x :x) tomb of the buguleir i think in well of spirits krokopatra is hard to solo by yourself with two people its easy she has 1100 health which is 
to the average wizard because the first thing 3000 health with good helpers not even the final boss of marleybone is better even with the boss helpers and getting there big ben diffulcty for the average marlybone wizard is 10/10 and the difulcty for the average marlybone wizard for the tomb is 10000/10
