Well that took a lot less effort to find than I thought it would, given how few WHF RPG things I can usually find on the internet:
This section gives you all the details of Chaos attributes or mutations (the terms are almost interchangable), which can be gained by the followers of Chaos. All those affected by Chaos attributes are referred to as mutants, regardless of whether they are Daemons, Champions Of Chaos, Chaos...
wfrp1e.fandom.com
Some highlights include: Extra eyes, growing a beak, a blood rage, having your arms replaced with axes, growing bird feet, being perpetually on fire, turning into a chaos spawn, turning into a coward, being always surrounded by a cloud of flies, turning into crystal, turning into Luffy, growing eyestalks, losing all facial features, having your face turn into a flaming skull, losing your head entirely, growing a mace tail, losing your mind (literally), growing another head, having rotting flesh, growing a scorpion tail, becoming beholden to the ministry of silly walks, and turning into a vampire.
someone clearly had a lot of fun with this list but I never want to roll on it
That's a 1E list it looks like. Strangely enough a lot of those mutations are familiar from the 2E list, so maybe the list hasn't changed a ton between editions aside from rule changes. I do feel the need to mention a few things about mutations.
While the D1000 table looks intimidating, and it is, there are actually mitigating factors for aspiring champions of Chaos. If you're dedicated to a particular god of Chaos, then you don't roll on the D1000 table, you roll on a personalised D100 table based on your god, and you only roll on the D1000 table if you roll 93-100. Now, the personalised table is generally better and less likely to screw you over than the D1000, but it still includes undesirable mutations.
Another mitigating factor is that certain followers of chaos have particular traits. There's the Inured to Chaos trait, which makes it so that if you have at least one mutation, you have a bonus (+10%) to resisting any futher mutation. Followers of Khorne and Slaanesh typically have this. Followers of Tzeentch typically have the Controlled Corruption trait, which gives them a -10% penalty to resisting mutations but lets them roll twice and choose the result they like better from the Mutation table. The Chosen of Chaos Talent also gives the same effect but provides no penalty to recieving mutations.
A few notes on Chaos Champions and mutations. In terms of mutations, you can recieve a number of mutations equal to 1d10+ your Toughness bonus. If you get more than that number of mutations, then you instantly turn to Chaos Spawn. Certain mutation results also turn you into Chaos Spawn, or have the ability to turn you into a Chaos Spawn under specific situations (rolling Chaos Were then getting another mutation while you're in your Were form instaturns you into Chaos Spawn). Another note is that Chaos Champions have something called the "Rewards of Chaos". When they do something particularly notable for their gods, they get to roll on the Rewards table, which can give them a mutation, Chaos Armor, Chaos Weapon, Daemon Weapon, Chaos Steed, Daemon Steed, turn them into an Exalted Daemon etc. One of the results for Rewards of Chaos is "Gifts of the Gods", which is yet another table that has specific "benefits" for each Chaos God, which is basically a mutation but it's not considered a mutation by the game so it doesn't contribute to Spawnhood. It's also usually beneficial. Usually.
But of course, the most important part of the Rewards of Chaos Table is the Eye of God roll, which is 98-100. The Chaos God pays attention to the Champion. If they have 6 Gifts or Rewards and less than 6 Mutations, they turn into a Daemon Prince and get whisked away into the Realms of Chaos. If they have 6 or more mutations, they instantly turn to Chaos Spawn. If they have less than six mutations and less than six Gifts/Rewards, then they get Chaos Armor and a Daemonic Weapon, or their existing equipment gets stronger.
In conclusion, being a servant of Chaos includes a ridiculous number of tables and rolls. Randomness is inherent, and while there are some very powerful boosts a person can get, Spawnhood is around the corner in every decision you make and the Chaos Gods are fickle. The thing about this though, you do this enough times and statistically some absurd monsters come out the other end.
—and it could come down to that.
