Phlegethite Margrave, Isis

Family: Phlegethite

Medium fiend (phlegethite), lawful neutral

Armor Class 22 (natural armor)
Hit Points 104 (16d8 + 32)
Speed 40 ft., fly 80 ft. (giant eagle)

14 (+2) 15 (+2) 15 (+2) 22 (+6) 22 (+6) 20 (+5)

Skills Arcana +13, Insight +13, History +13, Investigation +13, Nature +13, Perception +13, Persuasion +12, Religion +13
Saving Throws Int +13, Wis +13, Cha +12
Damage Resistances thunder
Damage Immunities fire, poison
Condition Immunities poisoned
Senses truesight 120 ft., passive Perception 23
Languages Common, Infernal
Proficiency Bonus +7
Challenge 21 (33,000 XP)



  • Multiattack. Isis can use her Frightful Presence. She then makes three attacks: one with her tail and two with her claws in giant scorpion form; two claws and one beak in giant eagle form; and three slams in all other forms.
  • Tail (Giant Scorpion Form Only). Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 7 (1d10 + 2) piercing damage, and the target must make a DC 17 Constitution saving throw or take 22 (4d10) poison damage and become poisoned for 1 minute. On a successful saving throw, the target takes half as much damage and isn’t poisoned.
  • Claws (Giant Scorpion or Giant Eagle Form Only). Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 6 (1d8 + 2) slashing damage.
  • Slam (Sow, Cow, or Humanoid Form Only). Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 2) bludgeoning damage.
  • Beak (Giant Eagle Form Only). Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 5(1d6 + 2) piercing damage.
  • Frightful Presence. Each creature of Isis’s choice within 120 feet of her and aware of her must succeed on a DC 20 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature’s saving throw is successful or the effect ends for it, the creature is immune to Isis’s Frightful Presence for the next 24 hours.
  • Magic Missile (1st-Level Spell; Requires a Spell Slot). Isis creates three darts of magical force. Each dart unerringly strikes one creature she can see within 120 feet, dealing 3 (1d4 + 1) force damage. When Isis cast this spell using a spell slot of 2nd level or higher, the spell creates one more dart for each slot level above 1st.
  • Witch Bolt (1st-Level Spell; Requires a Spell Slot). Ranged Spell Attack: +13 to hit, range 30 ft., one target. Hit: 6 (1d12) lightning damage and on each of Sisis turns for the duration, she can use her action to deal 6 (1d12 lightning damage to the target automatically. The spell ends if she uses her action to do anything else. The spell also ends if the target is ever outside the spell’s range or if it has total cover from her. When Isis cast this spell using a spell slot of 2nd level or higher, the initial damage increases by 1d12 for each slot level above 1st.
  • Disintegrate (6th-Level Spell; Requires a Spell Slot). A thin green ray springs from Isis’ pointing finger to a target she can see within 60 feet. The target can be a creature, an object, or a creation of magical force, such as the wall created by wall of force. A creature targeted by this spell must make a DC 21 Dexterity saving throw. On a failed save, the target takes 75 (10d6 + 40 force damage. The target is disintegrated if this damage leaves it with 0 hit points. A disintegrated creature and everything it is wearing and carrying, except magic items, are reduced to a pile of fine gray dust. The creature can be restored to life only by means of a true resurrection or a wish spell. This spell automatically disintegrates a Large or smaller nonmagical object or a creation of magical force. If the target is a Huge or larger object or creation of force, this spell disintegrates a 10-foot-cube portion of it. A magic item is unaffected by this spell. When Isis casts this spell using a spell slot of 7th level or higher, the damage increases by 3d6 for each slot level above 6th.


Isis can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. Isis regains spent legendary actions at the start of her turn.

  • Attack. Isis makes one attack with her claws or tail.
  • Spellcasting (Costs 2 Actions). Isis casts a spell from her innate spellcasting or wizard spell list.
  • Return to Geb (Costs 3 Actions). Isis causes a corpse she can see within 30 feet to burst into a shower of radiant stars leaving no trace of it behind. Everything it is wearing or carrying remains. Each creature within 10 feet of the corpse when it bursts must succeed on a DC 20 Dexterity saving throw or take 22 (4d10) radiant damage.


On initiative count 20 (losing initiative ties), Isis takes a lair action to cause one of the following effects. She can’t take the same lair action twice in a row.

  • Swarm of Scorpions. Isis summons a swarm of scorpions to attack her enemies. The swarm appears in an unoccupied space within 60 feet of Isis and lasts until the end of her next turn. The swarm can occupy the same space as other creatures and moves with Isis. Any creature that starts its turn within 5 feet of the swarm takes 14 (4d6) piercing damage and must make a DC 20 Constitution saving throw, taking 14 (4d6) poison damage on a failed save, or half as much damage on a successful one.
  • Solar Flare. Isis conjures a burst of intense light that illuminates the area around her. All creatures within 60 feet of Isis must make a DC 20 Constitution saving throw or be blinded until the end of their next turn. In addition, all undead and fiends within the area take 14 (4d6) radiant damage.
  • Burning Sands. Isis causes the ground to erupt in flames, scorching her enemies. All creatures within 60 feet of Isis must make a DC 20 Dexterity saving throw, taking 28 (8d6) fire damage on a failed save, or half as much damage on a successful one. In addition, the ground becomes difficult terrain until the end of Isis’s next turn.


The circle where Thammuz resides is cursed, creating the following effects. If Thammuz is killed, these regional effects end immediately.

  • Burning Sands. The ground beneath the creatures’ feet turns to burning sand, causing creatures to take 1d4 fire damage for every 5 feet they move.
  • Desolate Wasteland. The area becomes barren and devoid of any vegetation, except for some scattered patches of dead grass. The ground is dry and cracked, making it difficult terrain for creatures that are not immune to fire damage.
  • Isis’ Favor. Followers of Isis or those who perform a ritual to honor her gain resistance to fire damage and the ability to cast the spell “heat metal” once per day without requiring concentration while within the area of her regional effects. Additionally, any undead creature within her temple takes 2d6 radiant damage at the start of its turn.


Isis’ beauty is otherworldly, with a regal bearing that commands respect and fear. Her sheath dress is adorned with infernal runes that shimmer with an eerie red light, and her solar disk headpiece is a symbol of her immense power.

The undisputed rulers of the Burning Sands are Margravine Isis and Margrave Osiris. Consigned to the inner circle of the Phlegethon, they each control one side of the Burning Sands, visible by the towering spires of Isis temple and the enormous pyramid of Osiris’ tomb. Isis has nothing but disdain for the souls trapped with her in the Burning Sands. She hand picks the souls who worshipped her in life amongst the blasphemers (stretched supine in the sand), sodomites (who run in circles), and usurers (who crouch and weep). Each serves a purpose in worshipping her majesty, something she is holds primary above all other concerns. Those willing to fawn before her may be granted favors; those who dare to offend her suffer Isis’ fiery wrath.

Section 15: Copyright Notice

5E Foes: Infernal Bestiary. Copyright 2019, Mal and Tal Enterprises, LLC; Author Michael J. Tresca

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