How to Use – Combat Encounter 1 (difficulty 3)
The lemure is actually stronger than the manes (the demon equivalent.) Where the manes is a CR 1/8, however, the lemure is a CR 0. This reason is that the lemure will not go after PCs to attack them.
How should they be played? I would have them be wandering around more or less at random. If there is a large amount of lemures, I might suggest that they don’t go further than 10-15 feet from each other. Possibly, that no lemure will move to a place where it will won’t be within 10-15 feet of at least 3 other lemures. Or, you could provide a small area between two hills and say that they tend to go downhill and or are extremely unlikely to go uphill. That would basically keep them pent up in one area.
When a PC is next to a lemure, or when a PC moves away from a lemure and potentially lets it preform an attack of opportunity, I would give a small chance that the lemure will attack. One in three sounds about right. If you want to make them into a bigger deal, I might suggest that the attack is sometimes a grapple. It makes sense that they would mindlessly clutch at people that go near them.
A basic defensive tactic of devils, therefore, is to dig a moat, fill it up with lemures, and place fortified archers on the far side. [Spined devils work. So do skeletons.] You can’t move through a hostile enemy, and even if you move between them there is a major risk that one will grapple onto you, halting you in your tracks. Once trapped, you’ll be an easy target for the archers, and will take occasional attacks from any and all nearby lemures.
If you want even more of an obstacle, place burning coals or oil among the lemures. Like with all devils, lemures are immune to fire, but their enemies aren’t.
Combat encounter 2 (difficulty 4)
Outside the hells, a good strategy would be to load up a crate or two with lemures [devils don’t care about humane treatment, in case anybody’s wondering] and catapult it into the midst of the defenders. Even without the lemures attacking, they’re going to get in the way of the fighters in no small measure.
If the target is a building or ship, adding fire to the crate [or setting the crate on fire] is also a possibility. The defenders will need to rush to put out the fire, and the lemures are going to be getting in everyone’s way. Meanwhile, the attacking devils won’t be bothered by the fire at all.
Combat encounter 3 (difficulty 3)
A different type of idea is if the players have a mission to save the lemures from their fate. Perhaps they met the ghost of a paladin, who charged them to save the poor souls. Or, perhaps one of the lemures, in a rare moment of sanity, offered the PCs some vital information if they would take mercy on them, and release them from their present fate.
What the players have to do is kill all the lemures, in a way that will be permanent. If they have Bless, this will be ridiculously easy. If they don’t, however, than even if they have holy water instead, they probably don’t have more than one vial. Even if they do, they might not want to have multiple players using one of their hands to hold vials of holy water.
To complete the picture, I would have the land around them be swampy, or otherwise full of water. If they don’t sprinkle a dead lemure within moments [within one round of it being killed], its body will be lost among the swamp waters, and they won’t be able to give it a final death. What it will mean is that they have to be careful of how fast they kill the lemures. They can only kill them if the player with the holy water is nearby.
If they don’t have Bless or holy water, I would consider sending them on a small side quest to get a holy dagger that can function like Bless, but only in regard to damage dealt by the dagger. This will raise the difficulty even more, as now one of them needs to fight with a lousy weapon.
In this scenario, I might consider making the lemures more aggressive than normal. Perhaps the specter of final death is triggering a misplaced survival instinct in them. Regardless, I would have them move toward the nearest PC and try to attack him. Adding a few other monsters would be a good idea as well. It will both raise the difficulty, and ensure that the fact that only some PCs can kill the lemures doesn’t become too frustrating on the other players.