Your own summons start beating you up if they walk into your AoE spell. Can provide more details on a one-to-one basis if necessary.
Maybe you shouldn't hit your summons with Aoe? I hear if you hit players with it, the same thing happens.
But moving away from sarcastic comments, There was a thread about this earlier, except the spell in question was darkness.
It's the reason I'm not a summoner atm. They attack the caster if he uses an aoe on his own summons, and other players if they do it. It's crazy deadly.
you'll love to call out darkness upon your shadow spawns
My issue is that Undead summons attack each other due to their deadly fog effect
LE BUMPZ
... spiders attack each other when under effect of their fellow webbing
This has come up before, but I don't think it can be remedied, unless a dm has otherwise to say. I would suggest you don't use summons who have aoe effects that can harm their fellows if you don't want this to happen.
I am aware of it since my tiefling had issues with her shadows turning against her when she called out darkness, one year ago.
It is an old bug that has got no official answer, Zango. That is why I bring out awareness of it again.
And last, but not least, it is a main problem that affects summoners, making their life even more troublesome.
It has existed for years. Problem we have yet to find a solution for, and likely won't find one unless someone has time and effort to put into it to work out an AI script that negates the effects occuring.
You'll just have to manage, and many summoners have made it just fine up until now. It is unfortunately not on top of the big list.
I know its rather tedious to do when you have lots of summons out but I have found the control companion tool can be very helpful is remedying many of these situations as a temporary measure however the AoE effects are just something to avoid unless you're using a single summon.
If you want a summon to stop attacking something that it shouldn't be you can use the stand guard option which should stop them in their tracks (at least for 1 round).This usually gives enough time to use the player tool on the summon to re-direct it.