I'm preparing a "horde" combat, where a lot of zombies and skeletons charge against the party. The problem I have is that I don't know exactly how many units I should place, because it has some special rules:

  • The party is a barbarian, wizard (evoker), paladin and cleric (healer), all level 8

  • The party is in a really large room with no way out (until all undead are killed)

  • Undead come in waves of 20 per turn

How many waves should I place for a hard combat? (20 units each wave)

  • \$\begingroup\$ Do you need all the skeletons/zombies to be Medium humanoids? Because if they can be larger creatures or things like, say, a zombie beholder, that drastically changes the options for your encounter. \$\endgroup\$ Commented Sep 30, 2017 at 1:18
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    \$\begingroup\$ Have you ever played Starcraft? The reason I ask is that you seem to be trying to set up a variation of a zergling rush. \$\endgroup\$ Commented Oct 1, 2017 at 1:07

2 Answers 2


1.4 or 6 waves depending on how you view the battle

The DMG says that a hard encounter for 4 8th level characters should be worth 5600 XP. A single wave of 20 zombies is worth 1000 XP, but gets a x4 multiplier for a total of 4000 XP (DMG 82). Thus, by the book, 1.4 waves is enough for a hard encounter.

It's also worth noting that DMG 83 suggests that you treat each wave as an individual encounter:

For such encounters, treat each discrete part or wave as a separate encounter for the purpose of determining its difficulty.

If you do this, the total adventuring day XP budget for your party will be 24,000 XP, which means that your party should face about 6 waves for the entire day.

You'll need way more than that

In my experience, the DMG's encounter guidelines work best when the PCs are fighting a group of similar size--4 PCs vs. 4 monsters, for example. The further you get from a 1:1 ratio, the more likely that specific traits will make a huge difference. For example, 1.4 waves will be easy for this encounter--a single fireball will probably kill the first wave, and a turn undead would mop up the second. Your wizard can cast up to 5 fireballs (and sculpt spells), so that's probably the minimum number of waves you need before the encounter becomes anything but trivial.

Therefore, the easiest way to make a challenging encounter is to just keep throwing waves at them until the PCs begin to run out of resources. Even if you do set a hard limit on the number of waves, your players are never going to know if you planned for 2, 5, or 50 waves anyway. However, you will know if your evoker runs out of fireballs or the party starts to get overwhelmed, so you can just choose not to send in another wave after that. That's probably the best way to simulate an exhausting battle of attrition, especially if you're not going to use things like tactics or terrain.


By the book, 4 PCs of 8th-level has an XP threshold of 5,600 for Hard, and 8,400 for Deadly, bringing the total number of CR 1/4 creatures for the encounter you want to be somewhere between 28 to 41.

Computed as follows: 5,600 ÷ 50 (CR XP value for CR1/4) ÷ 4(encounter multiplier for 15+ creatures)= 28

I'd personally go with 41, maybe even kick it up to 45 or above, for a real challenge. The reason being, is that your party is fairly well equipped for this sort of situation:

  • One Fireball from the Evoker will kill most- if not all of these guys, if they just clump to the center. (Not even mentioning more powerful 4th-level spells like Wall of Fire- which is an encounter-ender here! and Ice Storm)

  • One Turn Undead from the Cleric will destroy most of them, thanks to his Destroy Undead feature. If your Paladin is a Devotion Paladin, the party can Turn Undead twice.

  • The Barbarian and Paladin can take a lot of those hits, and give them back, the Barbarian will likely one-shot every skeleton (the best way to do this is unarmed), while Zombies will be a little bit harder to kill (presumably the Paladin will Smite the zombies so they stay down).

Suggested Tweaks:

  • Use 45 Skeletons/Zombies, the exact ratio is up to you, but I'd lean more toward having more Zombies, but not leave out Skeletons, as they are faster (remember this, we will get to it), and they have a ranged attack option.

  • Have the Undead come in 15 at a time, and spread out where they are entering the room from, this will give you at least 3 rounds of combat and this way, your Cleric and Paladin can't Turn them all at once.

  • Position the "inactive" Undead at least 35 feet away from the nearest PC, this way, they will be out of range of Turn Undead, unless the Cleric moves closer or something. This is where the superior speed of the Skeletons come in, if you use Zombies with a speed of 20, they cannot get within reach of the PCs in one turn; with Skeletons, they will be able to move and attack at the same turn.

Also, for a fight of this scale, remember to use the Handling Mobs guide in DMG 250. Good luck!

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    \$\begingroup\$ Thanks a lot for the help 😊but actually that seems so low, i would expect from 100 to 200, because of fireballs and turn undeads, and i think the combat is way easier because they dont come all at once, if they keep the pace they can clear the 20 targets wave easily, maybe i have to test it to be sure. \$\endgroup\$ Commented Sep 30, 2017 at 0:57
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    \$\begingroup\$ If you let the 100 undead come all at once, the fight will be over in 6 seconds- and not everyone will get to participate. Pacing them at 15 at a time, actually makes it more difficult. \$\endgroup\$
    – daze413
    Commented Sep 30, 2017 at 1:02
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    \$\begingroup\$ The skeletons actually have ranged attacks, so you can spread them throughout the room and get more attacks in. Using those would probably help a lot. \$\endgroup\$
    – Erik
    Commented Sep 30, 2017 at 6:33
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    \$\begingroup\$ A benefit of using more, smaller waves is that you as the DM can determine on the fly if the difficulty is ending up in line with what you'd envisioned. Are they wiping the floor faster than expected? No problem: send another wave! Are the players about to die when you didn't mean for that happen? Hey, looks like that was the last of 'em. \$\endgroup\$
    – mattdm
    Commented Sep 30, 2017 at 15:57

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