Mutations, even usefull ones are viewed as evil in Warhammer, if you have one you best hide it or a Witch hunter may burn you alive thinking you harbor a Daemon in you. The Ruinous Powers, a title for all the Daemon gods united consist of 4 main Daemons:

Khorne, the Blood God: All Khrones servants lust one thing, the letting of Blood, it being their allies or their foes matters little, they fight for the sake of fighting and no other reason, the only other task for them is to survive and sacrafice skulls to Khorne to add to his already massive Throne of Skulls

Nurgle, Lord of Pestilence and Disease: Nurgle's Servants spread death and Disease as Humans give candy on Hallowen, they think it is a GOOD things that they are doing so and do it for the purpose of blessing others with the things that eat their organs and make their flesh turn green, they are more dangerous to be around than to fight at times, but some times poping these living Pimples can release things far worse than you can imagine.

Slannesh, Lord or Lordess(Depending on it's mood) of Unspeakable Pleasures: Slannesh uses a tactic diffrent from it's Demonic Kin, it uses appeal and beauty, and a slew of Drugs and other Toxins to make it seem preferable to normal life or boring normality, once it has you however it makes you bend in on your self in Excess and become a monster like it is, your body becomes warped and false, a fake image of perfection or a being that thinks it is beautiful when it appears to be a horse, it's minions also tend to scream in pleasure and being killed, as it sends their soul to Slannesh insantly.

Tzeentch, Lord of Change: The smartest and most Cunning of the Daemons, he see's all things on all plains as they happen and alters them to slowly insure he is the only Chaos god around in the end and that all belong to him, Divination Mages combat him by blackening his gaze, but in these dark times his eyes are wide open, looking at all of you, his minions have no ryhme or reason, they are mutated randomly and horrible, he either favors you one second, or is condemming you, nothing is certain with him, not ever your fate.

And now you know what your main Enemies are, Bledric the Burning Serves them all so mix them into each other and try to picture that in 12 foot Plate Mail that warps to fit in any mutation the wearer gets.