Reason Stealer

The reason stealer is a relentless, subterranean killer that murders other creatures to steal their intelligence. Reason stealers live below ground but make their way to the surface to hunt.

In its normal form, a reason stealer is a 4-foot-diameter puddle of grainy, brownish-yellow slime. If it has recently fed upon a creature possessing some form of intelligence, it can roughly mimic its victim’s shape. Such an assumed form is misshapen and blobby, and it only vaguely resembles the creature that the reason stealer killed.

A reason stealer doesn’t speak any language. When it steals a creature’s mind, it randomly mumbles words in that creature’s language.

Combat

A reason stealer lashes out at prey with a sticky pseudopod. Upon delivering the death blow to a foe with its pseudopod, it steals the opponent’s intellect. Once a reason stealer gains a modicum of sentience, it becomes a far deadlier opponent because it can use all the skills, feats, and spells it has absorbed from its prey. Sentient reason stealers ceaselessly search for new prey because they are desperate to avoid returning to their previous mindless state.

Devour Mind (Su): A reason stealer transfers an opponent’s Intelligence score to itself upon dealing it a killing blow with a slam attack. This process also heals the monster of 5 points of damage per point of Intelligence gained. Upon devouring a mind, the reason stealer has access to any of the dead opponent’s other ability scores, skill ranks, base attack bonus, and base save bonuses, and it can use any of these characteristics that are higher than its own. It also gains the use of the opponent’s feats and any prepared arcane spells. The reason stealer understands that it must remove spell components from a victim’s body to cast spells. All these acquired features last for 24 hours. If a reason stealer devours the mind of a victim while it still has the abilities of a previous one, it uses the higher of the two (the new victim’s or its current value) for ability scores, base attack bonus, base save bonuses, and skill ranks. It also gains any feats and spells possessed by the new victim that it did not already have.

Improved Grab (Ex): If a reason stealer hits an opponent that is its own size or smaller with a slam attack, it deals normal damage and attempts to start a grapple as a free action without provoking an attack of opportunity (grapple bonus +9, including a +4 racial bonus on grapple attacks from the sticky substance that covers its pseudopod). If it gets a hold, it has the option to conduct the grapple normally, or simply use its pseudopod to hold the opponent (–⁠20 penalty on grapple check, but the reason stealer is not considered grappled). In either case, each successful grapple check it makes during successive rounds automatically deals slam damage.

Grotesque Form (Su): A reason stealer that has devoured the mind of a creature with an Intelligence score of 1 or higher can shape its body into a bizarre reflection of that creature. If the reason stealer has abilities gained from more than one creature, it assumes a form similar to the last one it killed. A reason stealer with a humanoid form can wield weapons, using the fighting skills of any victims it devoured. It always retains one pseudopod with which to attack. A reason stealer can maintain a grotesque form as long as it has an Intelligence score.

Source: Monster Manual II, page 178. This creature’s statistics block has been updated to version 3.5 as given in the D&D® V.3.5 Accessory Update for Monster Manual II.