Cultist

A cultist on the party's side is a defector. He came up to the rogue last session and offered to talk, because his cell murdered his sister and he wants the temple burned. Use him as a guide and a witness, not a sword. AC 12 and 9 HP means one bad reaction roll from a guard captain ends his run.

In play, he opens doors the party shouldn't be able to find, knows the password to the inner sanctum, and can fake a chant well enough to walk a robed party through a checkpoint at Deception +2. His Religion +2 lets him explain what the sigils mean and which altar the relic is bolted to. The Ritual Sickle stays in his sleeve unless something goes badly wrong, in which case he will swing it at +3 for 1d4+1 slashing plus 1 necrotic, mostly to prove he is committed.

The exit conditions are grim. Either the cult catches him and the party has to choose between rescuing a sniveling traitor and finishing the mission, or the party uses him up and he dies clutching a holy symbol he no longer believes in. Both are good endings. The boring one is the one where he survives, joins the adventuring party, and turns into a permanent NPC. Don't let that happen.

If the party is genuinely kind to him, give him one moment of grace: he names the next cult cell, draws their sigil in the dirt, and walks out the door alone. Players remember the cultist they spared more than the ones they killed.

Write his real name on a card before session. It is not the name on his robes.

A cultist is a level 0 NPC with a knife and a bad idea. AC 12, 9 HP, +3 to hit with a Ritual Sickle for 1d4+1 slashing plus 1 necrotic. Alone, this thing dies to a single longsword swing. The cultist works in groups, in robes, in candlelight, and in the wrong room of the dungeon. Run them in clumps of four to eight, never as a solo encounter, because the threat is the chant and not the blade.

Lead with the scene. The party kicks open a door and finds twelve cultists in a circle, mid-ritual, with a bound captive at the center. The cultists do not fight intelligently. They fight to finish the chant. Have half of them keep ritual-casting (no real spell, just narrative pressure: a sigil burning brighter, a captive convulsing, the room temperature dropping every round) while the other half move to intercept. Cultists who reach a PC swing the sickle once and try to bleed the player onto the floor as part of the ceremony. The 1 point of necrotic damage is mostly flavor, but say it out loud every hit so the players feel the wrongness.

These NPCs do not retreat individually. They retreat as a unit when the ritual breaks. Once the captive is freed, the leader is dropped, or half the cultists are down, the survivors flee for stairs or a hidden exit, screaming about their patron. Let one or two escape on purpose. They become recurring faces.

Deception +2 and Religion +2 mean cultists are useful before initiative more than during it. The merchant who sold the party suspicious incense, the priest at the wrong temple, the cousin at the wedding: all cultist statblocks waiting to slip a sickle out of a sleeve.

Pin the cult's sigil somewhere the party can see it before the fight starts. The image, not the kill count, is what they will remember.