"You think that I do not know what you dove winged freaks are thinking?! It will not be that easy even for you guys." Adrian thought as he already sized up the three angels that are in the battlefield.
Adrian might not be able to kill them but that does not mean that he could not escape them. It is also the fact that they have not showed hostility openly which is why Adrian did nothing to them as well. Adrian deliberately chose an area where there is a higher concentration of players than NPCs.
Adrian knew that the players will not attack him compared to NPCs. He also chose the area that is belonging to the influence of the dwarves since they have a deal with them. In fact, there are actually three Faceless arch Priest that have been summoned and each are trying to summon the Faceless Arch Fiend.