I feel like the difficulty in this game is highly inconsistent and erratically shifts all over the place.
For the most part its way too easy, but the LV 18 Crypt is brutal and the boss is a nightmare.
I think the LV 12 Crypt hit the sweet spot in terms of difficulty, especially the boss and the golem fortress was a bit too easy but very close to the sweet spot.
I actually like the slower leveling because it gives you more time to grind for equipmenzt and learn to fight the enemies before you overlevel.