azaroth
13
well in my case it do in going by side and climbing (in exemple if i go into inner coutward, npc will no more spawn outside the wall near the cart if I killed them before), you need to avoid the strong point of npc (near main entrance in inner castle courtyard, those one will not close before killing boss) so far succeded to train at level 20 18 thralls, and lost 7 (i take newborn thralls)