well i understand your problem:
first: Zagan isn't your problem is is only level 20. but if you take a good look around you'll see nestdais 3 of them they spawn level 23 demons so with three of them and Zagan you'll be seeing your death comming very soon.
so you first action is KILL THE NESTDAIS as quickley as possible while moving around, before the can spawn enemy's!!!!! then zagan will be no problem for you.
