Waldenbrook for -300

Hello all. I am so disappointed. I had a promising hurtling weaponsmith. Precrowned twice with vanquiser and Sun's Messenger. Cleared fire tower and water temple very easy. Then i had a big stash of junk weapon that i started to melt. I had lured Glod in the downstairs and killed him with no other problems. All in town seems fine(all npc didnt attack me, and i smithed for some time, when a guard started attacking me. I teleported him away. And keep smithing for some more time. After that Waldenbrook came and kick my ass. -300 hp with 2 hits.
I have smithed many times with the same way. Why some npc was attacking me? Is it because i was permanent invisible? Is it because i use Glod equipment? I am confused and i really dont want this to happen again. ://

This should be in the yasd section btw :) there's generally a few reasons dwarftown goes hostile, number 1 reason while smithing is gaining the aura corruption. Other than that is killing residents. Sometimes when trading places with a npc they go hostile, then killing them will piss off dwarftown.