During Marvel Comics' Dark Reign storyline all of the Avengers were replaced by the darker versions of themselves known as the Dark Avengers, and Scarlet Witch's replacement has Marvel's most disgusting powers. Each Dark Avenger has a similar skill set to that of the hero they are standing in for, but June Covington, AKA Toxie Doxie, puts a disgusting twist on Wanda Maximoff's powers.
While Toxie has telepathic abilities and can create energy blasts, she also some truly gross powers. Not only does she have surgically implanted gills, but she also has neurotoxins in her blood that will kill anyone who comes in contact with it, poisonous breath that melts the skin off her victims, super soft bones that diffuse kinetic force, glands that allow her to dislocate her joints, and antiseptic spit to help her heal wounds. She wasn't always this way though. Before she joined the Dark Avengers, June Covington was an extremely gifted geneticist and biologist who became fascinated with perfecting the genetics of humans after meeting the brilliant Edward Wynne, whose only thing keeping him from perfection was a small birth defect on his arm. After some failed experiments, she decided to experiment on herself and manipulate her own genetics, ultimately perfecting them and resulting in her gaining these grotesque powers. Toxie Doxie is the way she is because she turned her own body into a deadly horror show.
While she is the Scarlet Witch of the Dark Avengers, they don't have too much in common besides the telepathic abilities and the costume. She enjoys hurting others with her magic powers, such as when she was imprisoned for inducing cranial explosive failure on 18 people during a prayer meeting for special needs children. This is how she met the incredibly dark Norman Osborn. After he helped her escape, she pulled a Harley Quinn and secretly became his doctor, started a romantic relationship with him, and returned the favor, helping him escape imprisonment as well.
After happily joining Osborn's Dark Avengers, Toxie Doxie took on many of Marvel's heroes and even bested Doctor Stephen Strange in battle. She took him down by using one of her most disgusting powers, her poisonous breath. Calling it her kiss of death, she breaths into his mouth, and reveals just how much of a lunatic she is when she mentions she wishes more than anything that she could watch him die. Not a peaceful death either, it would have been one where his skin would bubble and fall from his body. Doctor Strange did not expect her to have these abilities, and that is partly why he was so easily taken out by her.
There is no denying that Toxie Doxie has the most disgusting powers in the Marvel Universe, and they have come in handy to her multiple times. Besides the breath, her blood that can kill in seconds that she can easily pass through scratching her enemies. Those surgically implanted gills of hers helped her survive having her mouth and nose webbed shut by Spider-Girl, and her glands that distribute megadoses of "relaxin" allowing her joints to easily dislocate makes escape a lot easier. On top of all of that, she has an enhanced pain threshold, allowing her to keep fighting even when injured. Sure, Toxie Doxie may only seem like the Dark Avengers' Scarlet Witch in name and costume, but that doesn't mean she doesn't have some incredible, even though revolting, powers of her own.