Spellcasting. The apostle is a 5th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 14, +6 to hit with spell attacks). It has the following wizard, warlock and sorcerer spells prepared:

Cantrips (at will): fire bolt, toll the dead, prestidigitation, frostbite, blade ward, lightning lure, true strike

1st level (4 slots): burning hands, shield, chromatic orb, expeditious retreat, cause fear, charm person, hellish rebuke.

2nd level (3 slots): alter self, blindness/deafness, arcanist's magic aura, darkness gift of gab, mirror image.

3rd level (2 slots): counterspell, enemies abound, feign death, fireball, erupting earth, fear.

Crimson Amulet, Heal. Upon crushing this amulet the Cultist restores their hp for 5d4+2

Crimson Amulet, Magic Restore. Upon crushing the amulet the Cultist restores 3 spell slots of their choosing

Crimson Amulet Blood teleport  (Apostle). Upon crushing the amulet the apostle can  teleport to a location marked with their blood. If the Apostle waits 3 turns after crushing the amulet he can summon a demon to help aid them. 

Crimson Amulet, Demon: Upon crushing the amulet the user sacrifices half of their remaining hp to turn into a fiend this can also be used to turn anyone with a similar amulet into a demon( Dm discretion). 

Cape of the Mountebank: The magic item cape of the mountebank

Mark Bearer. Lieutenants and Generals (apostles) of the Crimson Cult have been given the task of finding a worthy vessel for their Matriarch the red lady Magda to possess. The lieutenant or general can channel their blood taking1d6+3 damage into a poisonous attack harming anyone not worthy taking 1d6+3 poison damage and have the poisoned condition . Those who are worthy the blood takes root forming a tattoo on the wounded part of the body cursing them and marking them.

Rapier: Melee Weapon Attack: +4 to hit, reach 5 ft. one target. 1d6+1 piercing damage

Blood Portal: The caster  takes 1d4+3 slashing damage opens a portal connecting two points in sight of the caster maximum range 300ft

Blood Magic: The caster takes 1d4+3 damage using their blood to strengthen one of their known spells +3 to spell attacks and with +3 to their spell save DC . This ability grants the user access to new spells (listed below). Duration 2 turns

Blood Magic, Blood Spear: The caster summons up to 3 red crimson spears taking 1d4+3 damage for each spear summoned making 3 ranged spell attacks dealing 1d8+3 damage on hit, the caster can target the same person or multiple people. The caster can choose to hold on to the spears and make an attack with them later. The spears will disappear after 2 turns or after Blood Magic ends.

Blood Magic, Blood Armor: The caster coats themselves in their blood taking 3d4+3 damage and increasing their AC by 4 and resistance to their choice of  slashing, piercing or bludgeoning damage. The duration is 3 turns or until Blood Magic ends.

Blood Magic, Twin Spell:  The caster takes on the sorcerer's twinned spell feature. When you cast a spell that targets only one creature and doesn’t have a range of self, you take damage equal to double the spell’s level to target a second creature in range with the same spell (1 damage if the spell is a cantrip). ex 1st level 2 damage, 2nd level 4 damage and so on. 

Blood Drain. The creature touches the target, the target makes a CON save DC14 on success no blood is drained on a failure blood is drained and the target takes 1d6+3 damage whatever damage they take is healed to the creature.

Blood Sacrifice. Biting down on the amulet to let all the magic flow through you and building pressure culminating in an explosion of crimson flame and blood range 30ft radius DC15 DEX save next to the caster, DC14 DEX save 10ft from the caster DC13 DEX save 15ft or more from the caster DEX save 6d6 for damage full damage on a failed save, half as much damage on a success.