Originally Posted by
Grunty
Since My Hero Academia was mentioned here, i was having a bit of fun thinking up a manga style display of Marrow's powers, after recently pondering on her potential character motivations in relation to Dawn of X.
However for that i would go with changing her growths from being strictly bone to being say a "carbone based psychic reactive bio-synthetic compound" (just made that up), that naturaly takes the shape of bones because of her subconscious. Though having "bone like growths" would be a still fitting descriptions of her powers.
Now this might sound like an unneeded change, but it could lift some perceived limitations on what she can do with her powers, based on what writers or readers might know of bone as material for tools.
To further evolve her powers she could also gain the ability to change their physical properties while still in contact with her body, even if just held in the hand.
For example taking a page from Eijiro of My Hero Academia she could harden them to diamond level strength or sharpen her knives to have moncular edges. Though getting incredible brittle in the process (like how it looks in Marvel vs. Capcom 2) would be a fitting drawback.
But it could now also go the other way. Soften the growths to a point where she can move or shape them like a clay. Creating tendrils for attack (something she displayed in X-force) or mobility (see the protagonist of The Spire for how even thin tendrils could help with that) or even something mundane like patching a hole.
Let's apply this to one of the X-men's usual punching bags. A big dumb Sentinel.
With new controll over her growths and their properties. She takes an energy blast by hardening growths into a shield like carapace on one side of her body. Any damage she still sustains could be handled by her healing factor (i would judge at a 1/2 Wolverine). So she goes right for the offensive. Pulling a knife out and softening some growths on her back to create a few tendrils, that she uses to catapult herself into the air.
While there she rapidly reshapes the knife into being the size of a 2 meter saber and hardens the edge to moncular sharpness.
Then she pulls herself back to the ground and brings the blade down on the Sentinel's head. On the ground her tendrils turn to dust and her sword shatters into pieces from exhaustion, but behind her the Sentinel falls appart in two neat halves.
Of course not even close to what characters like Storm and Iceman can do. But a lot better than just having her knives harmlessly bounce of the Sentinels's head.