Earlier today, I stumbled upon this question.
As I often do around RPG.SE and another sites, I initially misread the title, and contemplated for a second why someone would look for a way to raise undead papercraft skeletons in a medieval-like RPG Setting.
Not many seconds later, I was dumbstruck by the sheer awesomeness of the possibility of a army of Origami Undead Skeletons of Destruction.
The idea of a Evil Papermancer was so chaotic that it is going to be my next main villain. Period.
To do something like this, one needs a class that can support really well controlling multiple creatures, may "fold" new origami creatures on the fly, and be able to have a somewhat wizard-like repertoire of spells, to complement the "evil caster" stereotype.
However, the action economy of such a class is simply hellish - once you have 10 summoned creatures on the table, things start breaking down quickly. The party wouldn't be happy to deal with the waiting times during all the actions of those Origami creatures, and they will have a serious disadvantage fighting so many enemies at once. This gets even worse when their main enemy can summon different things at any moment, to adapt to the situation.
So, here's my question:
How a DM should proceed to create an interesting fight against a swarm of different creatures, and still keep the pacing of the game? Should a DM avoid pitting the party against all the enemies at once, and let them fight parts of the brood of our villain one at a time?