Brotherhood of the Penitent

Assassinate. During its first turn, the agent has advantage on attack rolls against any creature that hasn't taken a turn. Any hit the agent scores against a surprised creature is a critical hit.

Evasion. If the agent is subjected to an effect that allows it to make a Dexterity saving throw to take only half damage, the agent instead takes no damage if it succeeds on the saving throw, and only half damage if it fails.

Sneak Attack. Once per turn, the agent deals an extra 14 (4d6) damage when it hits a target with a weapon attack and has advantage on the attack roll, or when the target is within 5 feet of an ally of the agent that isn't incapacitated and the agent doesn't have disadvantage on the attack roll.

Spellcasting. The agent is a 9th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 15, +7 to hit with spell attacks). It has the following wizard spells prepared:

Cantrips (at will): light, prestidigitation, mending, fire bolt, blade ward (bonus action)
1st level (4 slots): alarm, illusory script, magic missile, shield
2nd level (3 slots): alter self, darkness, detect thoughts, silence, misty step
3rd level (3 slots): counterspell, feign death, dispel magic, haste, tongues
4th level (3 slots): arcane eye, dimension door, psychic lance, wall of fire
5th level (1 slot): immolation, steel wind strike, teleportation circle

Multiattack. The agent makes two shortsword attacks.

Shortsword. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) piercing damage, and the target must make a DC 15 Constitution saving throw, taking 24 (7d6) poison damage on a failed save, or half as much damage on a successful one.

Light Crossbow. Ranged Weapon Attack: +6 to hit, range 80/320 ft., one target. Hit: 7 (1d8 + 3) piercing damage, and the target must make a DC 15 Constitution saving throw, taking 24 (7d6) poison damage on a failed save, or half as much damage on a successful one.

Guided Strike (Recharges after a Short or Long Rest). The agent grants a +10 bonus to an attack roll made by itself or another creature within 30 feet of it. The agent can make this choice after the roll is made but before it hits or misses.