KMS 1.2.197 Zero

I don't believe there's a level requirement. It's the map with the 100~250 label near the top left. You need a 환생의 태엽 to enter the dungeons. They cost 5 coins each. I wouldn't recommend entering at that low a level, solo anyways. The monsters are all 140 and a bit over 4k physical attack, 7.4m HP, 20% Defense, and physical resistance. The boss has 14.8m HP, 6k atk, Seals every 25s for 15s, heals full every 30s, and has a 15s DR with 80s CD. I find it doubtful 13x would be able to DPS it down fast enough, especially if you suffer any lag, as you'd need two Reindeers to recover from each hit, plus an 1800 tick poison, and 50% HP attacks. Things in there huuuuurt. With Wind Cutter, Advanced Throwing Weapon and Earth Break, I can kill it before it heals. Doubt I would be able to so easily without ATW, especially if I get caught in a Seal by chance. You only get two Death Counts in this dungeon by the way.

You don't unlock the dungeon. You need an entry item to access the dungeon, which can be bought in the shop in Zero's Temple.
Critias dungeon is a WIP.

Ah I see. Thanks for the replies, was wondering what that item was for in the shop. Not really aiming to complete the dungeon, just curious what it looks like inside and try out the dungeon for fun.