This actually isn't that bad if you have a method of doing it, yes healing combos are recommended but can be done without it.
If you want some more in depth details about it I suggest checking
here.
The main thing is to keep from knocking the summoned zigreds below 40hp or everything gets healed. So make sure that they are within a killable range block if needed to reduce your damage if your attack can't quite kill it. I would also avoid using summons as their attack range can sometimes cause the summoned zigreds to be sacrificed.
That being said an alternative strategy is to summon and cause the zigreds to be sacrificed early as the heals will just over flow while you stall. When it runs out of zigreds to summon then it's just you and the main one.
Belt set up should be something like this.
Giant
3 lifes
2 scrolls
If you have 8 slots can add
1 vampire
1 scroll
This should help you sustain through the entire fight. Good luck!