Very cool mechanic. I really like the idea here of having the attack be automatic and the strategy is all in the positioning. Yes, it's hard LOL. I don't think that's bad in itself, I would just say try to always have a possibility of escape. When it picks up, it's easy to get into a no-win corner, so to speak =D.
One thing that I think would help this is if the camera showed more of what was going on. It's biased towards the back of the room, so if you "use" the back of the room, you're at a disadvantage, especially if there are walls blocking the view and something suddenly appears. Lots of ways to handle that, but I totally get that a lot of them are tricky and not something easy to do in a month-long game!
Another one might be if the power-ups were a little heavier in their effect. Like the vampirism one granted me 0.1, I was like aww snap haha. You've got something good here, though. Difficult or no, it's fun to play repeatedly!