A lot of the oj, yellow, blue mobs don't aggro unless you're directly on top of them.
In addition to the lower level mobs not aggroing unless you're on top of them, the higher ones in certain parts of the dungeon aggro from far away (and run out through walls).
In addition to the lower level mobs not aggroing unless you're on top of them, the higher ones in certain parts of the dungeon aggro from far away (and run out through walls).