Do we need unusual nature in our D&D books?
Unusual Nature is an ability given to some non-biological creatures, like undead, constructs, elementals, and some creatures that just have weird anatomies like aberrations. All it says is "This creature does not require air, food, drink, or sleep." Most of the time it's not even a true addition to the creature, as it was mentioned outside of the statblock in the paragraphs of lore text, which just makes it easier to find the information.
Boggle (VGtM)
Here is another example of a monster not really meant for combat, the Boggle. However, the boggle is meant to be annoying, and has a multitude of powers to back that up. Which, in my opinion, is a good example of why even non-combat NPCs should have Stat blocks. If only because someone is going to try and punch them for their trouble. As a creature that could be described as an oiled-up goblin, boggles are fey creatures born of loneliness. Orphans, widdows, and isolated sages may unintentionally summon one if they are near a place connected to the feywild.
Boggles like to cause mischief, which is where the PCs are likely to encounter them. Stealing items, scaring animals, leaving non-flammable puddles of oil everywhere. An NPC could hire a group of PCs to exorcize a ghost, only to find a Boggle instead. Alternatively a Boggle could manifest for a PC if they are in an extremely isolated place, like a prison, or out lost in the woods by themselves. Allowing some form of companionship and a possible avenue of escape.
Boggles are only CR ⅛. They are not going to last long in combat at any level of the game, and as such will flee at the first sign of real danger. If the PC’s elect to capture the creature rather than kill it, that’s going to be hard. Boggles can produce oil puddles as an action, leaving difficult terrain and possibly causing someone to slip or get stuck in it’s wake. Furthermore, the boggle can use this oil to escape grapples, slip through tiny cracks, or stick to walls and ceilings like a spider. If that doesn’t sound like enough, the Boggle can also create a rift through any opening (like a door or window frame, even the gap between jail bars or between the bed and floor) to another place 30’ away. Allowing them to reach though, attacking or grabbing something, or even just teleport away.
In the changeover, the Boggle somehow gained a +2 bonus in Perception, presumably from expertise, but it had no such ability to replace or listed in it’s current stat block. In a weird twist, the reformatting of this stat block might actually make it harder to parse, as it has both types of oil listed in two different places.