Anyway, here we go! My 5e Phycomid.
Phycomid – Small Plant
A.C. 10 (Natural Armour)
Hpts: 99 (18d6+36) [52 - 144]
Speed: 10' (Forestwalk)
Proficiency Bonus: +2
Str: 4 (-3) Dex: 14 (+2) Con: 15 (+2) Int: 3 (-4) Wis: 5 (-3) Cha: 6 (-2)
Saving Throws: Constitution +2
Skills: Stealth +4 (Fungoid Form)
Damage Resistances: Acid, Poison
Condition Immunity: Frightened, Prone, Sleep; Lacking Imagination
Damage Vulnerability: Radiant
Senses: Blindsight 60' (Blind Beyond) ; Passive Perception: 7
CR: 3 (700 xp)
Forestwalk: The Phycomid ignores difficult terrain caused by trees, bushes or other natural features found in a forested area, even if they are not caused by nature.
Fungoid Form: The Phycomid gains advantage on checks to pass as innocuous fungi in an environment typical for such things.
Lacking Imagination: The Phycomid is immune to all Illusion spells and effects.
Multiattack: Phycomid makes two Digestive Spume attacks.
Digestive Spume: Ranged attack; Range 50'; One target; +4 to hit; Hit: 22 (4d10) Acid damage and target must make a D.C. 12 Constitution saving throw, or begin to lose 1 point of Constitution at the start of each of their turns (Save at end of each turn ends). This is a disease effect. Those killed by the disease immediately begin to rot, and in 1d6+6 hours time become a new Phycomid. A Remove Affliction or similar can also stop the ongoing Constitution loss.
Err.....you need a spot of cream on that I think...