Question about swarms

[DungeonmasterCal]

If a spell or spell like effect is cast on a swarm, does it affect the swarm as a whole or just one member (assuming the saving throw is failed).

 

[Shin Okada]

As a whole. By the rule, entire swarm is treated as one creature, though there are a lot of special rules and exceptions. Read Monster Manual, both Swarm entry in the main section and the grossaly.

 

[DungeonmasterCal]

Thanks...that's what I thought. But I'm at work and the online SRD sites seem to be down.

 

[Dr_Rictus]

The most important exception is that any effect that targets only a specific number of creatures (including single-target effects) has no effect on a swarm.

The exception to the exception is that mind-affecting effects can target the swarm as a single individual if the swarm has a hivemind.