Actually, I believe you can have two autocasts, they just cant be of the same spell type. For example, you can have autocast inner fire on along with autocast flame arrow(wteva the priestess ability is called). No need for triggers try it n see if im wrong
Inner Fire and Heal cannot be auto-casted at the same time because they are a normal spell. Normal, as in a spell that normally affects a unit. As for Searing Arrows (and every other Arrows spell) is a spell that affects your attack and give it effect. And because they are spells of different types, they can be set to auto-cast at the same time.
You could trigger it i guess... It'd be like making AI though. You'd have to make an ability and specify when the unit should cast it.
It shouldn't be too hard for heal spells.
Unit within Range has >max life.
Heal
But without triggers and easy stuff, you can't make 2 or more autocasts.
Ghan has said he has fixed this. Monovertex please confirm this fix. This was only a problem with people that had signatures in the upper levels like not the special members but the respected members.