I am currently prepping Maze of the Blue Medusa as the first part of my Clash of the Titans campaign. Many of the monsters I just intend on swapping them with 5e equivalents and not worrying about CR – with a few exceptions. Psathyrella is an exception. Here is the first draft/conversion for 5e.
Duelist, singer, sea captain, collector, inferior artist, (reluctant) jailer of immortal threats, occasional obsessive lover. Intelligent, dissolute, powerful, and feared. Wealthy, well-informed, but somewhat indifferent to the passage of years. Her beauty rivals the gods.
Legendary Resistance (3/Day). If Psathyrella fails a saving throw, she can choose to succeed instead.
Petrifying Beauty. Psathyrella was cursed by the goddess Aphrodite, but unlike her sister, her beauty was not taken away – it was enhanced – anyone who looks upon her is petrified by the power of her comeliness. When a creature that can see her eyes starts its turn within 30 feet of her, she can force it to make a DC 18 Constitution saving throw if she isn’t incapacitated and can see the creature. If the saving throw fails by 5 or more, the creature is instantly petrified. Otherwise, on a failed save the creature begins to turn to stone and is restrained. The restrained creature must repeat the saving throw at the end of its next turn, becoming petrified on a failure or ending the effect on a success. The petrification lasts until the creature is freed by the greater restoration spell or other magic. Unless surprised, a creature can avert its eyes to avoid the saving throw at the start of its turn. If the creature does so, it can’t see Psathyrella until the start of its next turn, when it can avert its eyes again. If the creature looks at Psathyrella in the meantime, it must immediately make the save. If Psathyrella sees herself reflected on a polished surface within 30 feet of her and in an area of bright light, she is affected by her own gaze.
When a creature is petrified, Psathyrella may instead choose to petrify the soul of the creature. The creature’s soul turns into a pristine statue and its body becomes a husk that will obey Psathyrella (use a zombie equivalent of the base creature or some other undead). A creature whose soul is petrified can not be resurrected in any way without Psathyrella’s permission or, alternatively, when she dies.
Psathyrella has control over who she can unpetrify which she can do with a touch if she so chooses.
Special Equipment – The Reflecting Mirror. It can never reflect Psathyrella. Any mirror reflected in its surface will explode. She wears this mask when she is not hostile.
Multiattack. Psathyrella makes three attacks only one of which can be her snake hair.
Phobos. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3) piercing damage. This weapon ignores AC or any other barrier rolling to hit against the targets natural AC only (10 + DEX). It automatically hits and kills any target that Disengages or otherwise tries to run away. Any spell targeting Psathyrella is absorbed automatically by Phobos, converted into a fear spell and redirected at the caster as a reaction.
The Writhing Blade. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 5 (1d4 + 3) piercing damage. The weapon attaches and bored into its target doing 1d4 + 3 necrotic damage at the start of Psathyrella turn. It cannot be removed unless Psathyrella will it or she or the target is dead.
Claws. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 9 (1d8 + 5) slashing damage plus 4 (1d8) poison damage. Psathyrella may also grapple the target (escape DC 19). Until this grapple ends, the target is restrained and takes 15 (3d6 + 5) bludgeoning damage at the start of each of its turns, and Psathyrella loses her Multiattack and Claw action. On a successful attack, she may also remove the petrified condition from the target if she wishes.
Snaky Hair. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 31 (4d12 + 5) poison damage, and if the target takes any poison damage it must make a DC 18 Constitution saving throw or die. If they make the saving throw they slowly begin to petrify (see petrifying beauty).
- Move. Psathyrella moves up to her speed without provoking opportunity attacks.
- Snaky Hair. Psathyrella makes one attack with her snaky hair.
- Petrified Earth (Costs 2 Actions). Psathyrella causes stone spikes to erupt from the ground in a 30-foot radius centred on her. The area becomes difficult terrain until the start of her next turn. Any creature, other than Psathyrella, takes 9 (2d8) piercing damage for every 5 feet it moves on those spikes.
- Numbing Claws. Psathyrella makes two attacks with her claws. If both attacks hit the same creature, it takes an extra 7 (2d6) poison damage and must succeed on a DC 18 Constitution saving throw or become paralyzed until the start of her next turn.
- Look at Me (Costs 3 Actions). Psathyrella can force a sighted creature she has grappled to see her eyes and be affected by her gaze.
When fighting in an honourable duel she wears her mask, does not grapple, claws or hair, and uses only Phobos. If fighting against a dishonourable foe she does not wear her mask and uses both Phobos and The Writing Blade which she can summon to her hand as part of her attack or multiattack action.
Psathyrella has mellowed in her old age and is content to maintain the maze-prison as both warden and prisoner. Though the gods that condemned her have passed onto the Astral Plane she continues on. She is not quite a god but she is a mythical and fae creature. If she takes a liking to the PCs she may offer one of them to be her champion. This can be represented as a level in warlock and/or the patron spell effect from DCC. She is not very demanding as a patron of her champion, so long as the prison is maintained (she may call on her champion if the prison is under serious threat) she wishes to only get reports, recordings, books and so on from the outside world delivered to her. She will provide boons in the shape of patron/warlock spells as well as snake, poison and certification related spells. She does however still hold a grudge against Aphrodite and would reward any champion that despoils any of that goddesses temples or relics – but she wouldn’t be so gauche as to suggest doing anything of the sort (at least not directly).