I was making my way throught the first secret mission/dungeon. Near the end of it, there were 2 walls that open (I assumed when you push the stone slab/pedestal, but these ones open after I got the tome). There were alot of enemies in the other sides of the walls, so I thought cool, seems like a trap and maybe a challenging fight.

But I noticed enemies aggro through all walls, so I thought ok, a little cheesy but I will drag as many as I can to the openable walls because I had a TNT. Kill a bunch at once. (Edit: turned out they opened later)

Bug: I accidentally threw the TNT and it went straight through the openable wall. So I thought, what else goes through? I could attack through it and kill enemies on the other side. Creepers could be actived, detonating and killing enemies around it (and me if I stayed too close). Edit: Enemies can also attack me through the wall, I just didn't get hit earlier.

So what was supposed to be a cool fight/trap thing, basically became no challenge at all and I killed 25+ enemies very quickly without taking damage or being in any danger.

This was on the second last default difficulty and I'm only lvl 7 (lvl 8 afterwards), gear score 10. I shouldn't be able to skip 'tough' encounters like this.