Over time, I’ve designed soul forms for Shifter, and I finally finished making a lineup!
1 soul (Glow Shifter): Most of the soul's energy went to healing his eye, so it's not very impressive, but he is stronger than before. 2 soul (Splash Shifter): Fingerpaint themed. Since he's playing around with his new strength, his attacks are more dynamic and colorful, but kinda unfocused. 3 soul (Paint Shifter): A tad drippy, but stable enough not to be scared by it. His "arms" are actually intertwined vines, which he can unwind to attack with. 4 soul (Canvas Shifter): Feather pen themed. Has added ink blots and drawings to his attack repertoire, providing him with a free-form fighting style. 5 soul (Stitch Shifter): Has realized he isn't limited to a human amount of arms and is taking advantage of it. He can sprout arms from the slits in his stem, and can rip the pins out of himself to use for attacks. The colored pins on the ropes are soul attacks! 6 soul (Sigma Shifter): Limitless and free from anything tying him down. His coloration and shading has a more painted look than his surroundings. The ropes are prehensile and function as a third set of arms! 7 soul (Shape Shifter): Given the power to turn into anything he wants... He just turns into whatever catches his fancy. His original form does hold some comfort, though.
I imagine that for forms 2-5, his attacks would be themed a bit after his appearance, including bullets/vines. 6, though, can just use all the attacks of his previous forms, along with several new ones.