[3.P] Interesting PC vs army battles?

[Bovine Colonel]

So for the conclusion of my campaign, the main villain will most likely have successfully collected the MacGuffins required for his universe hard reset plan. In order to stop him, the players, who will be around level 12~14 at that point, are most likely going to have to carve a path through his entire, not insignificant army, along with perhaps a good-sized village of frost giants and other miscellaneous allies. How would I make such a battle interesting?

[Oscredwin]

What's the party makeup?

Have them find/craft a rod of Widen. It's a metamagic that doesn't see much use in play, but it's tailor made for fighting armies.

[AslanCross]

If they're going to have to blast through phalanxes of large numbers of troops, it will either be underwhelming ("Oh look, another encounter with 500 1st level warriors that we can one-shot.") or boring ("Okay, that leaves 203039 more to go.").

Are you, as the DM, willing to keep tabs on the HP of thousands of troops (who likely only have one hit die each anyway)? Is that something the players would enjoy?

I'd break it down into several encounters, each with unique twists. For example, they could break through the defenses at a weak point and use something to throw the rest into confusion (such as turning the trebuchets around and launching magical projectiles). Then they could deal with a few large or very powerful enemies (In the confusion, the enemy's Battletitans could have been let loose, so the PCs have to stop them lest they get eaten), and use the chaos to accomplish their mission.

[Gavinfoxx]

Don't actually have an army really threaten them. Really. Just describe the slaughter as they walk through (or fly above, or bypass or whatever) like gods.

Or point out a bunch of army killing and flight spells, so they can do the strategic bomber thing, to thin out and rout the army...

I statted up a level 9 Druid for army killing once. It was pretty cool.

http://www.thetangledweb.net/forums/profiler/view_char.php?cid=54924

[Aharon]

You could use the homebrew unit template: http://www.giantitp.com/forums/showpost.php?p=7325672&postcount=27

[NineThePuma]

Don't expect the battle to be magnificent. Frame it as multiple small encounters or start laying the groundwork for them to maybe find a way to avoid having to carve through it.

However, something to consider is if the Heroes have allies they can call in on their own. A Bad Guy trying to get rid of reality is rather likely to have angered off at least some of the more powerful creatures as well. The Great Wyrm Dragon who has been mentioned a few times in backstory might be made aware of what is happening when the PCs tell an old inn keeper who happens to be a retired Dragon Shaman. The Cleric's god can't intervene directly, but serves as a focus, sending many powerful clerics into battle. The PCs are left feeling less "I am a Sexy Shoeless god of war!" and more "Baator^Yes, our army is awesome!"

This lets you skip several sessions of combat that might end up rather meaningless in the long run, or might go horribly sour because of one or two bad rolls.

Instead, I would suggest the following:

As the Heroes close in on the villain, they have to face some last ditch defense efforts from the villain's mooks, delaying tactics, anything to throw their game off. Try to make this scene and session very intense emotionally, with a feeling of being under pressure. But as the heroes breech the villain's inner sanctum, the ritual that he's performing rises to a climax, and they are left only with the villain grinning at them, and he utters four words.

"You are too late."

There, the session ends, and you ask for their character sheets. Cut session early, if possible. Depending on where game is held, send them home or leave yourself.

Make sure that you've got an arrangement for next week set up still.

When they come in, hand them (new) character sheets. Make them very basic character sheets, with only a name, and being fairly low level, but still obviously within the archtype of the original character. Frame it where they've been hired to be an escort for a caravan, and pass maybe the first hour of the session this way. Then let them get sidetracked by ruins nearby, haunted by some sort of spectre or ghost.

They stumble across... The Party, in some bizarre half state of being, and learn from them that the world has been changed from its natural state!

Where you take it from there is, as always, up to interpretation, but I figure it's a decent setup.

[Karoht]

So for the conclusion of my campaign, the main villain will most likely have successfully collected the MacGuffins required for his universe hard reset plan. In order to stop him, the players, who will be around level 12~14 at that point, are most likely going to have to carve a path through his entire, not insignificant army, along with perhaps a good-sized village of frost giants and other miscellaneous allies. How would I make such a battle interesting?

Rule 1-Let them throw the first punch.
Well, technically the bad guys have already thrown down the gauntlet.
But let the party start the event off with a bang, especially if they have something clever planned. Much more fun, might resolve itself quickly and easily.
IE-If your party had a druid, let them cast their Treant and Siege of Trees and have fun with that.

Rule 2-Encourage hit and run tactics.
Terrain to suit. Have them hit a flank or a strategic target, and then get out of there. A while later, go back, hit more stuff.

Rule 3-Flyers and Stealth.
Use them. Ground only armies have no chance VS a single wizard with Fly and Fireball. At which point the ground army only serves to exist in order to be a target to be carpet bombed.
Meanwhile, some flying and invisible casters can be incredibly useful. They don't have to be very high level, just high enough to be in the air and mobile and able to shoot back. Stuff that targets reflex saves are great for shooting down most flying casters. If not, archers mounted on flying mounts, or even charging classes with flying mounts (air cavalry) works. Seriously, if you don't want your army carpet bombed via Wizard, you need to make the air into it's own battlefield.

Rule 4-The Army Starts Buffed
The Army doesn't need to waste time buffing, they're already buffed. Some fantastic buffs out there which can be incredible for helping to keep this army alive. Don't focus on damage necessarily, focus on survival, boosting saves, resistances, spell resistance or DR, and possibly any kind of mass area healing.
Spell Immunity Communal is an awesome buff.
Firebrand can be pretty lethal if used tactically.
Elemental Body on your healers is awesome. They can then hide in the ground.

Rule 5-Illusions
Illusions over the army can mask line of sight, sometimes line of effect. The army can be illusioned to make it look much bigger than it is. Whole sections can be illusions. It's great because it keeps the player party unbalanced, they don't know if the whole army is an illusion designed to distract them or not. Either way, great way to keep your important units protected. The party can't fireball the cleric if they can't see him. And if he's invisible AND hidden in a cloud of fog? Or hiding in a pit that looks like the ground?

Rule 6-Summons and Such
If a party knows they are up against an army, summons are just much more likely to be employed, especially if the party has prep time. Which can almost turn into it's own little mini-army on the side if things get out of hand.
Don't forget your NPC's can do this as well to buy time. My advice is have your summoners summon before battle, before they buff up. Keep the high end expensive summons invisible/illusioned/hidden as much as possible. Invisibility Sphere works, or just some good dug in positions.
Earth Elementals are great summons, they can be hiding in the ground and spring out at a moments notice. They are also effectively invincible while part of the ground, really not much is going to hurt them there.

Rule 7-The Battlefield
Terrain is a big deal. It's going to entirely shape how your combat goes. Even if some of that Terrain is illusionary.
Terrain also involves things like pits, trenches, and traps. Dig pits, fill with spikes. Cast Illusionary Terrain (I think that's the name) and watch the fun. And remember, you can't charge over rough terrain, plenty of spells leave terrain as rough, so use that to your advantage.
Sleetstorm is a fantastic spell for slowing down melee, preventing charges, and blocking line of sight. It's also great when you have to retreat. And it's a conjuration spell so you can't just dispell it, if memory serves me correctly. It''s even great for if casters need a place to hide, heal up, buff up, summon more stuff, etc.

Rule 8-Healing
A small army that survives is more fun to fight (faster turns, easier to keep track of) than a large army that dies easily. Healing is a big chunk of army survival. Have a few Clerics around the feat Quicken Channel. When the army gets hurt, they can double channel to AoE heal, or they can channel and cast a spell. If you have many Clerics, this equates to many channels and many spells. You can easily keep the army healed and continue to be offensive/defensive casting.

Rule 9-Formation
Rank and File works fine for the front liners with sword and board and spear. Anything behind them should be loosely scattered as best you can. You don't want any more than 3-4 people deep. Any gaps form in the line, they're all holding actions to move in and fill that gap.

Rule 10-Reserves
Always always always keep a few aces in the hole. Or in this case, those frost giants? Yeah, hold them back a bit. Have them go wade in and make a right mess of things once the party is engaged with other issues. Or, when your army is losing, have them full berserker attack. By which I mean, these guys just dive in and go nuts, not actually Rage or anything (unless that's your thing). Heck, have a few on flyers, try and jump-grapple another flyer and pile drive them into the ground below. Suicide tactics and all that.
By the time you bring out your reserves one of two things should have occured.
1-Party has destroyed a good chunk of your army but has likely expended a good chunk of their resources, send these guys out to reinforce and further reduce those resources.
2-Party is in a vulnerable position. They're holding the line against your forces but are otherwise contained. Drop your giants on them and increase the pressure, but carefully. Drop is both literal and figurative here. If your party has their back to a wall just holding the line, and suddenly see the frost giants lumbering forward, that is going to make them probably consider changing into that second pair of pants they brought with.

[CTrees]

Resist the temptation to give everyone in the army one sorceror level and a wand of magic missile, no matter how glorious it would be.

[Roguenewb]

Here's what I'd do (and have done): use encounters of 16 individuals each 6 levels lower than the party. That's technically a CR ECL+2, but it really won't be. Optimize the groups well, a group with 3 clerics, 2 chargers, 6 Sword and Board area controllers, 3 skirmish archers and 2 arcane casters, focusing on knocking down other flyers, and suppressing buffs. There are other teams you can make as well. If each of "platoons" is carrying a mission forward, the party might find themselves distracted.

If you've pushed the story well enough, they should feel the urge to stop all the platoons, and maybe, if you're lucky, they'll get caught up and fight a ton of platoons, and put themselves in a war for you.

Waves of level 1s will be a trite encounter. They'll shred it.