[Soyweiser]

Also, having slaves with natural regen, or throwing in a master that casts personal regeneration upps the survivability of your slaves a lot. If they get over 200 fatigue, the hp damage gets healed away.

Also, if you summon earthpower, the slaves will get the reinvigoration even without having earth magic themselves.

Of course mistform, air shield and mirror image raise the survivability of your slaves a great deal.