Well I can't say I dislike the dungeon system the way it is, cause I don't. But I was wondering if it would be possible for the The Humanoid Lair (Level 10+), The Orcish Complex (Level 25+), The Melket Lair (Level 40+), and the The Castle of Undead (Level 60+) to require 1 player only. I know its currently 2 players but hardly possible to find anyone willing to complete these dungeons, and I get they are low level and somewhat useless so why not have it so it can only be 1 player required. It would give solo players something extra to do on their own and overall I feel wouldnt hurt the game as players can't "mass level" in these beginner dungeons.

Also maybe add a Dungeon Point system. I know there are rewards throughout the course of doing dungeons an x amount of times, but could be more appealing with a system where we gain points and can in turn trade in the points for items, more dungeon tickets, exp boosts and whatever else suits your thoughts ^^. Just examples. I know the task system is like this as well, but the dungeon system wouldn't be a bad idea as well, rewards do not need to be the same was an example.

Make the current monsters in each dungeon an "Elite" form of the monster they are portraying. And a little bit harder. (Elite Bandit, Elite Demon)

Open another client log into another character. Problem solved. MC is not illegal* "what is illegal is being active on 2 characters using mana healing ect." as long as you are not 100% active on 2 characters you can just log one in to help with the +1.