I have been converting AD&D 2e Planescape monsters to 5th edition for my upcoming game, and thought I'd start a thread for our monster conversions.
To start off, here is a solid guideline I put together for guesstimating 5e Challenge Rating using 2e XP Value:
Next I use James Bowman's Simple Conversion Guide for 2nd edition. Awesome stuff.
Finally I reference Surf's D&D Blog for fine-tuning and hardcore number crunching.
Monsters that have been converted so far include:
- Astral Searcher CR 1/2 (by @Quickleaf)
- Vargouille CR 1/4 (by @Quickleaf)
- Cranium Rats CR 2, 4, or 6 (by @Quickleaf)
- Dabus CR 1 (by @Quickleaf)
- Yagnoloth, Yugoloth CR 11 (by @Quickleaf)
- Maelephant CR 8 (by @Quickleaf)
- Widdershins CR 9 (new monster by @Quickleaf)
- Minion of Set CR 3 (by @delazar)
- Gohei P'oh CR 1/8 (Kara-tur monster by @Wicke)
- Aleax CR variable (by @delazar)
- Nic'Epona CR 4 (by @delazar)
- Spirit of the Air CR 5 (by @delazar)
- Vortex CR 1/2 (by @delazar)
- Marraenoloth, Yugoloth CR 7 (by @delazar)
- Decaton, Modron CR 9 (by @delazar)
- Nonaton, Modron CR 10 (by @delazar)
Medium aberration, Unaligned
Hit Points 9 (2d8 HD)
Speed 0 ft fly 40 ft
STR 6 (-2), DEX 10 (+0), CON 10 (+0), INT 1 (-5), WIS 10 (+0), CHA 14 (+2)
Damage Immunities poison
Damage Resistances bludgeoning, piercing, or slashing damage from non-magical weapons
Condition Immunities exhaustion, grappled, paralyzed, poisoned, prone, restrained, unconscious
Senses darkvision 60 ft, passive perception 10
Languages none (see Possession)
Challenge 1/2 (100 XP)
Incorporeal Movement: The astral searcher can move thru other creatures and objects as if they were difficult terrain. It takes 5 (1d10) force damage if it ends its turn inside an object.
Possession: If the astral searcher reduces a creature to 0 HP, the target falls comatose and the following turn the astral searcher enters their body, possessing the victim and gaining their stats (but not their personality). Speech, skills, spells, and special abilities at first aren't possible, but gradually become available as the searcher adapts to its new body. In most cases the victim is now dying, but in some cases it may take several days for the victim's psyche to be destroyed (at the DM's discretion). During this time it is possible to save the victim by exorcising the astral searcher with greater restoration, heal, banishment, or wish. It is also conjectured astral projection could work. The victim will remember little of their ordeal.
Psychic Claw. Melee Attack: +4 to hit, reach 5 ft., one creature. Hit: 7 (1d8+2) psychic damage and target must succeed on a DC 12 Charisma saving throw or lose a precious memory, and along with it a skill proficiency and a spell slot (if any). This effect lasts until the target finishes a short rest.
The bane of travelers to the Astral Plane, astral searchers are mindless shells created by intense emotions - usually anguish - of travelers from the Prime Material Plane. They appear as vaguely humanoid silvery-blue mist. Violent death, combat, and incredibly destructive spells on the Astral Plane create astral searchers. These beings wrongly believe the confusion, fear, horror, and rage under which they are created is the natural state of things. Congregating around astral conduits, they attempt to slip into either the Prime or the Outer Planes in order to take a body. In some cases a searcher adapts so well that they remain hidden within a community for a long time before being exposed.
Rarely, a searcher in the Astral finds peace in its tortured existence, devoting itself to protecting astral conduits; such searchers don't appear to hunger for physical form like others of their kind and are known as "astral guardians" by planewalkers.