The Laughing Crow is a moniker whose voice I borrow: a rascal who is abrasive but honest, curious, and outgoing.
What is a mob?
A shuffling horde of zombies, a swarm of goblins falling over each other to reach the PCs, clockwork insects and animated cutlery are all "mobs". While individually they are relatively harmless, the encounter you have prepared for the PCs calls on there being a large group of them.
Rather than statting up each individual monster, it might be a better idea to create one or two "mobs" instead, with the creatures working in unison and effectively counting as one, big threat. If you want to make an encounter more challenging, or you have multiple players, feel free to combine a single Mob creature with a larger, singular threat.
An example would be a swarm of Goblins with a shaman, or animated objects with a single animated cupboard.
A Zombie Horde in action
The fact that the Mob is composed of many creatures should be part of its High Concept:
- A swarm of Goblins
- Zombie Horde
- Carpet of creepy crawlies
When you as the GM invoke this high aspect, you can easily use it to boost Grapples, or perhaps a Mental attack directed at a PC who might have a phobia for bugs. It also can be used in defensive actions - I mean, ever tried to hit a swarm of ants with a stick? You can hit only a few at once, and there just seem to be more of them.
Conversely, clever players can also compel this High Concept - after all, they are being close together, so an attack that hits an area normally will deal additional damage. It also means that someone who might have appropriate powers - such as an insect controller versus a swarm of giant wasps - could affect the entire swarm at once, rather than an individual insect.
The Mob's Trouble, and other aspects, would be dictated by the base creature type. So a swarm of Goblins might have Short Attention Span just like any single one might. And zombies are Slow and ponderous so likewise a Zombie Horde would be too.
Have you considered...
..that a player whose character is a famous idol might be locked in a social conflict by a Gaggle of Fan Girls? Or that there is a lot of social conflict generated by the party's healer being mobbed by A colony of devoted lepers?
Not all conflicts involving a swarm are physical in nature, and not all can be solved by brute strength. In fact, A mountain of legal paperwork in Mental Conflict with the party's barbarian likely is a never-ending compel on his Trouble aspect!
Stunts and Refresh
In most circumstances, a Mob of creatures has the same kind of stunts as the base creatures have. That said, the fact that they are a Mob does allow them to do a lot of things faster, or perhaps in an area.
Consider a stunt that allows a Zombie Horde to get +2 when grappling a person, while a Goblin Swarm might have a stunt that reads "they automatically place a Trap! scene aspect each turn, which they may invoke once for free". Likewise, a Swarm of Ants might have a Flying stunt, as well as one that allows them to attack everyone in a zone with one roll, as an Area attack.
Remember that while it represents a Mob, the creature's stats are otherwise treated as being a single monster. So it would get one single action each turn. This isn't just to make it fair to players, but the very idea of a Mob is to make less rolls in a turn, as well as provide inspiration for describing the scene.
Skills and consequences are very fluid, so this needs to be tailored to your game. In general, when in play and suffering damage, you want the Mob creature to take consequences that reflect its fractitious nature.
For example, a Goblin Swarm taking a consequence might suffer This way! No, that way! reflecting it not being as coordinated as it should be. A Wasp Swarm might suffer The Queen is Wounded! which can be exploited by clever players. Likewise, animated objects might suffer from Broken legs and twisted frames as their integrity is diminished.
In all cases you want to offer consequences not just as a mechanical description of damage or loss of integrity, but also offer cleverly named consequences that can be used by players who compel it in a creative manner. That way you really engage them and turn the encounter into more than a hack-and-slash.
Your opinion matters!
And now for a twist...
Consider these creatures as dynamic scene aspects, describe what their presence does. A swarm of wasps darkens the sun, the chittering laughter of a Goblin Swarm can be heard echoeing through the tunnels. A Zombie Horde shuffles and lurches, their undead hands battering down doors and barricades. A mass of pestilentious rats spreads disease, and all other living creatures flee the area, even fearlessly running past the PCs in a stampede!
Second, consider what happens when a swarm is damaged enough. It might thin out, but eventually it falls apart. Especially when the individual creatures might still be a threat (such as with Goblins) consider a Goblin Swarm in defeat to fall apart and "spawn" two normal Goblins - the sad remnants of an entire tribe.
You could use these survivors to be questioned, but they might also try to escape - and clever PCs might want to follow them to their treasure hold!