Can Undead Swarms Be Controlled?

[atemu1234]

So I'm going through Libris Mortis and I happened upon the Bloodmote Cloud and the Bone Rat Swarm. Supposing that a party went up against one and an evil-aligned cleric attempted to rebuke them in order to gain control of the swarm, could they? Or are they immune by nature of being a swarm?

[The Glyphstone]

RAW is a little ambiguous, but I think I'd allow it. Swarms are immune to single-target effects or effects that target a specific number of creatures, but otherwise have Hit Dice as if they were one creature. Rebuke Undead affects all undead within a specific radius, but with a cap of total Hit Dice rather than total individuals.

[St Fan]

I agree with the above analysis. Effects that rely on a number of hit dice rather than a given number of creatures are efficient against swarms. (For examples, calm animals can soothe an animal swarm.)

[Mr Adventurer]

This is great. So, what undead swarms are there?

[Psyren]

Not only can they be turned/rebuked, it's actually easier. Libris Mortis:


UNDEAD SWARMS AND TURNING

Because undead swarms are made up of many weak undead
creatures, they are more vulnerable to turning than normal
undead. For all purposes related to a turning check or turning
damage, treat the undead swarm as having only one-half (50%)
of its normal Hit Dice. Add any turn resistance only after halving
the swarm’s HD.

As for undead swarms, I'm not as versed with 3.5 monsters these days but Pathfinder has several - Skull Swarms, Bonestorms, Carrionstorms, Drocha, Hungry Mists, Ubashki to name some. You should be able to port these back to 3.5 pretty easily.

[The Viscount]

In addition to the aforementioned bloodmote cloud and bone rat swarm, there's also the corpse rat swarm and the ephemeral swarm,

Not sure how that turning undead rule would interact with monsters with the swarmshifter template.

[atemu1234]

Not only can they be turned/rebuked, it's actually easier. Libris Mortis:



As for undead swarms, I'm not as versed with 3.5 monsters these days but Pathfinder has several - Skull Swarms, Bonestorms, Carrionstorms, Drocha, Hungry Mists, Ubashki to name some. You should be able to port these back to 3.5 pretty easily.

Huh. I missed that. Thanks!

[Segev]

Control undead (http://www.d20srd.org/srd/spells/controlUndead.htm) targets 2 HD/CL worth of undead, so would also work on undead swarms. Control undead is not rebuke/command, though, so the halving of HD doesn't apply by the RAW. (You could probably talk a DM into allowing it, though.)

It's important to note that Necromancy spells which compel, control, or even possess undead are NOT mind-affecting, so the usual immunities to that don't work. You can even magic jar the undead, and any swarm with a hive mind. (Can't do it to one without, though; they still are immune to n-target effects.)

[Mr Adventurer]

Control undead (http://www.d20srd.org/srd/spells/controlUndead.htm) targets 2 HD/CL worth of undead, so would also work on undead swarms. Control undead is not rebuke/command, though, so the halving of HD doesn't apply by the RAW. (You could probably talk a DM into allowing it, though.)

I'd say it's less clear-cut than that - since the spell does still target creatures, I can see a DM ruling it falls foul of the Swarm immunity. So, check that while you're having the conversation with your DM, too.

While you're there, see if you can get them to agree those special rules apply to Mobs (DMG2) as well...

[Segev]

I'd say it's less clear-cut than that - since the spell does still target creatures, I can see a DM ruling it falls foul of the Swarm immunity. So, check that while you're having the conversation with your DM, too.

While you're there, see if you can get them to agree those special rules apply to Mobs (DMG2) as well...

No, it targets "HD of creatures." For it to target creatures, it would have to specify a number of creatures it targets. This is why even Chain command undead wouldn't work: it targets CL+1 creatures. But control undead targets "up to 2 HD per level of creatures." Which isn't a number of CREATURES. It's a number of HIT DICE WORTH of creatures. Which a swarm manifestly is.

It does say "no two of which are more than 30 ft. apart," but swarms are contained within squares 10 ft. on a side, so it won't run afoul of that.

[Mr Adventurer]

No, it targets "HD of creatures." For it to target creatures, it would have to specify a number of creatures it targets. This is why even Chain command undead wouldn't work: it targets CL+1 creatures. But control undead targets "up to 2 HD per level of creatures." Which isn't a number of CREATURES. It's a number of HIT DICE WORTH of creatures. Which a swarm manifestly is.

It does say "no two of which are more than 30 ft. apart," but swarms are contained within squares 10 ft. on a side, so it won't run afoul of that.

I mean, I disagree with your conclusions and I disagree with your reasoning, but I'm not interested in arguing with you. I was only pointing out that it's not as clear cut as other examples.

[Dalmosh]

The All-Consuming Hunger from the Forgotten Realms Underdark supplement is another undead swarm.

[Quertus]

Control undead (http://www.d20srd.org/srd/spells/controlUndead.htm) targets 2 HD/CL worth of undead, so would also work on undead swarms. Control undead is not rebuke/command, though, so the halving of HD doesn't apply by the RAW. (You could probably talk a DM into allowing it, though.)

It's important to note that Necromancy spells which compel, control, or even possess undead are NOT mind-affecting, so the usual immunities to that don't work. You can even magic jar the undead, and any swarm with a hive mind. (Can't do it to one without, though; they still are immune to n-target effects.)

I read the Libris Mortis entry as saying to count a 4 HD swarm as 2 HD to determine whether or not you could turn/rebuke it, but it still counts as 4 HD against your control pool.

Further, I would rule that, while you control the swarm, you don't control the individuals. Any individual undead remaining after the swarm is dispersed are uncontrolled.

[Segev]

I read the Libris Mortis entry as saying to count a 4 HD swarm as 2 HD to determine whether or not you could turn/rebuke it, but it still counts as 4 HD against your control pool.

Further, I would rule that, while you control the swarm, you don't control the individuals. Any individual undead remaining after the swarm is dispersed are uncontrolled.

The latter point is fiddly to consider, since technically they still have HD and control undead controls HD of undead, but at the same time, a "dispersed" swarm ceases to be a "creature" for almost all intents and purposes. I don't think the system expects PCs to have to deal with the aftermath of a dispersed swarm's individuals.