Amazing design and amazing abilities, but these guys have WAY too much health. Running into them is almost a guaranteed mission failure. If they spawned alone, 30-32 would have been acceptable, but they are always grouped up and this just makes them a living nightmare. I personally had to lower their hp to 20 and 22 in order to make the fights balanced again (I'm playing Veteran Ironman, a difficult i'm never going above or bellow).

So like i said, i suggest either lowering their health like i did or just making them pod leaders instead. That way you'd be fighting one custodian (later a master) and whatever others troops spawn with them.