I'm an EK 250 and I search regularly for these bosses in -1.
If you're also a low level as I am, I would recommend you never to run through the big room without knowing it very well.
First, there are too many monsters and the floor is quite confusing so that you can very easily get trapped.
Second, even if you know your way, you will get paralyzed sometimes by Spitter (which isn't the biggest problem) and if you are very unlucky, the boss Mindmasher may be somewhere hidden (even invisible) and you may get drunk (it took me some SSA, mighty rings and UHP to get out of trap with 8 monsters around me).
Very important: your biggest problem will always be the Hive Overseer and his summons (all the bosses, taken separately, are less dangerous than it and its summons). If you want/must kill it, use 'exeta amp res' to get it (just one if you're 300-) close to you and always focus your full attack on it.
As it is very slow, I usually lure all the other monsters (including bosses) to a place outside of its range and kill them without problems.