I haven't read to far yet, but the author really has two options at this point. Either the MC will be the most OP gary stu or they'll constantly put him into obscure situations that highlight some weakness. I mean his damage multiplier is broken, he ignores all defense/evasion, and he has perma stealth? Well the later isn't totally clear yet. It seems like attacking breaks stealth, but he can immediately go back in forever? The obvious counter here would be things that can see thru stealth (a common thing for game bosses to have), aoe damage, and dots/status effects. He doesn't seem to have any inherent speed bonuses or evasion and not sure if damage breaks stealth. Well at least his class is unique so we won't have boring PVP battles were shadow assassins play some lame submarine game on land. There might be a flag/foreshadow that he'll run into enemies that are immune to damage. The most you can hope for there would be some sort of condition the MC has to exploit on a case by case basis, but the vibe I'm getting is that this MC is destined to steamroll without planning anything.

Speaking of... one that always gets me is present here. The game just launched. On one hand players are clueless about basic game mechanics like quests, but somehow there is already a player economy, massive guilds, player rankings, and such a working knowledge about drop mechanics that one has to assume that there was heavy leaks or data mining during a beta.. otherwise how would people be familiar with half of this? Or had time to set it all up.. These types of stories rarely seem to lampshade it or even try to establish a passable excuse like I came up with above.