Gourmand: An ability for OD&D Fighters [CW: Blood]

I've had this on the back burner for a while, but reading this post about Fighters from Evie Willems of Spider Queen finally gave me the energy to finish it! Presented here is one possible way to make fighters a bit more exciting.

Inspired very heavily from a Strong ability in WhiteHack 2e. I love how this ability enables a type of diegetic advancement for fighters. The flavor I've applied to it is inspired by boss souls in Dark Souls and eating monsters in Nethack. This also doubles as my take on eating monsters.

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(For fighters)

When you slay a monster and consume its flesh (or its soul), you may take on an aspect of its power. Gain bonus Hit Points equal to the monster's total number of Hit Dice, and a property associated with that monster, negotiated between you and your referee. All bonuses last until you do this again.

Example: A fighter kills an ogre and consumes its soul. She gains 4 bonus Hit Points and +2 to her attack damage (the thing ogres do). She later does the same to a Cockatrice, losing these bonuses and HP but gaining 5 Hit Points and the ability to petrify a struck foe (with saving throw, once per day).

warrior eating a cockatrice. drawing i did last year while playing a lot of nethack