Creeper
Medium monstrosity, chaotic evil
- Armor Class 12 (Natural armor)
- Hit Points 23 (3d8 + 9)
- Speed 35 ft.
STR DEX CON INT WIS CHA 6 (-2) 13 (+1) 16 (+3) 6 (-2) 6 (-2) 5 (-3)
- Skills Stealth +5
- Damage Immunities lightning
- Senses darkvision 60 ft., passive Perception 8
- Languages --
- Challenge Normal: 2 (450 XP) Charged: 4 (1100 XP)
Charged by Lightning. A creeper that is subjected to lightning damage becomes a charged creeper. A charged creeper's explode action has double the blast radius and deals double the damage of a regular creeper.
Hiss. As a bonus action, the creeper prepares to explode next turn and emits a hissing sound audible out to 50 feet. The creeper's turn ends.
Actions
Explode. The creeper self destructs, emitting a thunderous boom. It dies, and each creature within 20 feet of it must make a DC 13 dexterity saving throw. Creatures within 10 feet of the creeper have disadvantage on the save. On a failed save, a creature takes 7d6 (25) thunder damage, is pushed 10 feet away from the creeper's corpse, and becomes subject to any ongoing magical effect the creeper was under when it exploded. On a successful save, a creature takes half as much damage, isn't pushed, and isn't subjected to any magic that was affecting the creeper. Objects within the explosion's area that aren't worn or carried also take the damage and, if unsecured, are pushed. The creeper can only take the explode action if it took the Hiss bonus action on its previous turn.
Spawned by Lightning. A creeper results from a phenomenon in which lightning or fey magic mutilates the corpse of a humanoid, combining it with surrounding vegetation. This process's wide area of effect generally converts all humanoids in a party. Consequently, their origins are mysterious--most say that creepers spawn from the darkness from which they often strike.
Recognizable Hiss. While creepers' origins remains mysterious, their behavior is commonly known. A creeper meanders until it sees a living humanoid, which it will then stealthily approach, hiss at, and detonate. Scary stories in stormy areas mimic the sound of the creepers' hiss, and adventurers in creeper-infested areas often bring cats, which creepers fear.
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Explosive Corpses. The dried corpse of a creeper slain pre-explosion is an explosive. One round after ignition it detonates with the force of a normal creeper's explode action.
Aw, man!
Creepers’ heavy offensive slant and single-burst-only damage make them very swingy monsters—one could drain no resources or slay an entire unlucky level 2 party. To avoid these problematic extremes, don’t use creepers against PCs below level 5, and even out the variance by using more than one creeper when they do show up.
Creepers, and Minecraft belong to Mojang. Image credit: Minecraft wiki and Vivi Werneck (https://tecnoblog.net/336774/quem-sao-os-creepers-em-minecraft/)
CR Calculation (Creeper)
Hitpoints comes from the fall damage heart conversion: 20 half hearts x 1.15 = 23. AC comes from its lack of natural armor bars in minecraft yielding an AC of 12 in the AC regression formula I wrote up. (I did consider docking it to make "kill the creeper before it explodes" to be an even more viable strategy). Those two poor values combine for a defensive CR of 1/8.
Offensive CR is a bit more complicated. The explosion DC is CON based, and set so that it gives DC 13, an appropriate DC for where I expected the creeper to wind up CR-wise. But it's DPR is ~(25*4 [DMG 249])/3 = 33, ignoring the disadvantage from being close to it. Thing is, the DMG 249 "AoE targets hit" guidelines are likely to be inaccurate in the case of the creeper, which gives players an entire turn to book it (though admittedly it's somewhat likely to be hidden when it hisses). In practice I'd be surprised if it normally managed to catch more than two players--a dpr of 16.6 (and of course, confident enemies will deal with the creeper by killing it before it can explode). Supposing that the disadvantage for close players is the equivalent of 1 extra player hit, I get DPR 25 DC 13 --- Offensive CR 3.
To be on the safer side with a monster that could quite easily one-shot low level players, we round up to total CR 2.
What about the charged creeper? The average group will probably have someone that knows that creepers get stronger when struck by lightning, and it's not a terribly common damage type for player characters to deal, anyway. So we don't include it in considering the base creeper's CR. However, a DM can send previously charged creepers at players or pair them with non-humanoids that deal lightning damage. So a 40 ft blast with 50 expected damage. That's reasonably going to hit all 4 players expected in a party if they don't manage to kill it. So, 200/3=66 dpr = base offensive CR 10, adjusted to offensive CR 9 due to low DC. That...honestly feels a bit high, given how often players of that level will be able to find and kill one quickly (or escape). So this time we'll round down from CR 4.5625 to CR 4 instead of rounding up.
Speed comes from the creeper's minecraft speed attribute (note the creeper will attempt to take the Hide action instead of Dashing most of the time.).