i think summoning is meant to be coupled with another school like hydro/aero/pyro rather than necromancy or used by itself. it makes sense if you think about it, most skill trees allow you to set up surfaces you can cast totems and incarnates on, and let you manipulate the field so your summons can do more damage. even blood rain is a good skill to use since blood incarnates/totems are very strong and allow you to maximize physical output if you need to. i think it'd be way too strong if i were able to summon an incarnate champion and a bone widow at the same time, two very bulky summons that do a lot of damage and have opportunist/can potentially teleport. enemy mages will melt in one or two turns even on higher difficulties

i get that it can seem underwhelming but playing as a summoner is really fun and adds a lot of versatility to combat aside from buffing teammates and doing damage. placing totems on high ground areas is also a cool way to manipulate combat