its Mammon week, it always happen that the mobs replaced...
Well. I've learned something.
It has been that way since the 7 sings things were introduced. You get different mobs in the competition week than in the validation week. Not all mobs are exchanged, but some are.
This page (http://www.lineage2.com/background/chronicle3/list.html) explains the story of the Seven Signs. The Nephilim are the soldiers of Anakim and the Lilim soldiers of Lilith. During the validation period, depending upon which side holds which seals, only certain mobs will spawn. It appears that Dawn won on your server, so Anakim's warriors get to take a break while all enjoy in hunting Lilith and her followers.
If you stay in necro/cata during exact time when validation wek turns to competition and vice versa, those mobs disappear for good few minutes (dungeons are "mobless" :) ) and are replaced by different ones.
If you stay in necro/cata during exact time when validation wek turns to competition and vice versa, those mobs disappear for good few minutes (dungeons are "mobless" :) ) and are replaced by different ones.
... and you get kicked out when it turns to competition week and you walk too close to a mob :)