A mid-core content for mid-core players.

[Kosmos992k]

It's an eventuality. However as I said at the beginning, this content it must not be a sure clear, like a 10% of clear rate. However the rewards system will not penalize the casual player, they keep taking the unique material from every mob or from the quests.

I'm sorry, but saywhatnow? You want people to pay tomes to run this, but they have a scant 10% or less chance to clear it? This challenging content with no time limit and more complex mechanics? Sorry, but you're not describing mid-core content, you're describing an hard core raid complete with punishing wipe mechanics. That 10% or less completion rate will relegate this content to the design room floor unless the rewards are worth wiping multiple times before winning. And if you want replayability (you seem to with the respawning and wandering mobs), then the reward is going to need to be good enough to entice people back again.

But again, you really seem to be describing something closer to hard core raid content, than mid-core anything.