How can I run fights involving large groups of creatures without slowing combat to a crawl?

Question

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.

Thus, a refluffled Pathfinder's Summoners Archetype Master Summoner is almost perfect.

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.

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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?

Answer 1

Sorta

There are things you can do make large battle scenes more tolerable in PF/3.5, such as;

1. Grouping Attacks - Similar units with similar attacks are grouped into 'volley' attacks that are dodged with either a saving throw, or are fewer attacks that deal more damage.
2. Placing Fights - creating larger 'maps' for fights with terrain that separates groups of combatants allows the players to use terrain and selectively engage enemies, turning a 'large fight' into a series of smaller fights.
3. Treating Groups of Enemies as a Single Creature. Roughly what the DMGII's 'Mob' template does, treat a group of weaker creatures as a single creature with it's own hp and attacks. HP being whittled away kills members of the group, but it still only has one set of stats (although probably a Swarm attack).
4. 'Battle', treating weak enemies as a terrain effect. They're rough terrain and deal environmental damage to the party, but they're not units with hp - by moving through them, the party is killing/fighting through them, but the party's real enemies and real goals in the scene are unrelated to them so they don't roll dice or do more than hinder the party. Like orcs in a LOTR battle, the party spends it's actions shooting down oliphants and stuff, killing orcs happens 'during' their other actions.
5. Waves, enemies come as relatively discrete encounters with a time pressure of if you don't wipe them out the next wave is going to arrive. In this case, the papermancer would be origami'ing new monsters as the party cut down the ones he has already made, and doing other things like sending waves of sharp-edged paper birds through the group, sending paper streamers in blue hues to 'flood' the party and ruin their footing etc (you can refluff a lot of spells to be origami).

But you shouldn't be hanging everything on a single battle anyway

Any good villain is foreshadowed. Paper mantis assassin striking the party in the night, learning about the man who wears a white paper mask and kills with paper knives, thugs wearing paper armour with paper swords (that are made from scrolls, and the thugs can activate them), an ally of the party being killed a paper chain that climbs singing into his mouth and chokes him to death at a dinner party, the climactic fight at the hideout alongside their allies, the papermancer boarding a paper dragon to escape, the final confrontation on the mountain where he defends the diggings of the Jade Lotus society's attempt to resurrect a dead god, defeating the papermancer who fights to the very last with no advantages to defend a man who isn't worthy of that loyalty, thereby giving the PCs yet another reason to hate Marcus Stein, aka Xaoyao Luyfu, the Hidden Master of the Cult of the Jade Lotus.

Etc etc. You introduce, you create importance, you cause confrontation, you (hopefully) escalate the confrontation, and then you add twist to season, either twisting to make the character relatable or sympathetic or to make them even more horrifying than the party ever dared suspect.

That's what makes a memorable villain. Large fight scenes can be story-required, like if you foreshadow that the papermancer if given time can create a paper-army, and then the party gives them time, but they do not create memorable villains or highlight interesting story features.

Answer 2

The first part of the answer is right in your question - you could probably use the swarm rules, maybe add fluff to the swarm's phase a little...
http://paizo.com/pathfinderRPG/prd/bestiary/creatureTypes.html#swarm-subtype

For the second part of the question, IMO, and there is no answer that is universally right, it depends on what makes the most sense how to deploy the minions. Because your players will question it. If the force is obviously just for the sake of playability broken into smaller chunks, they will notice it. If there is more than one entry to the hideout, on the other hand, they'll except them both to be guarded. Is the NPC a paranoid warlord or a reclusive sage of best forgotten knowledge? The first will probably have all his cardboard warriors at his side, to be better protected, the second will place them so nobody will reach him and disturb his studies.