Gameplay? I'm thinking a trap based fighter who can paint on the ground or even walls! You could have something like Kindred's target board except make it different colors that you can mix up to 2 for stat modifications or something. Magic paint ^_^
Passive- The color palette you can select up to two different colors to mix which will give you different stats
Q- Channel to doodle on the ground or terrain, the longer you channel the more complicated the painting becomes the more damage it will deal when someone walks close to it, doodles on terrain would shoot out forward from it while ground paint would erupt, both of which slow the enemy.
W- Swipes the paint-brush to launch one of three random paint blobs, red does a magic crit, blue lowers MR, and Yellow knocks them back.
E- Splashes green paint in a line that speeds up allies and enemies that walk through it, however allies gain a dash attack to their next auto-attack (Think like Ekko's roll but instead of a warp it's a simple dash) but on yourself you can reactivate it to launch a fair distance and place the current level of a fully charged Q at the destination.
R- The bristles of the brush sweep away an enemy inside a blank canvas making them untargetable for the duration, however during this time you paint exaggerated wounds on them which become real when they come out of the painting. You can move while this is active however you are slowed down since you're painting on a canvas as you run.
I dunno, I just thought of this off the top of my head and if I gave it more thought I could make something more creative. But the R is kinda like Skarner ult but is more like you take yourself and one enemy out of the equation of a fight, while it can also be used to pick-off enemies by dragging them into your team. shrugs might be too similar but I'm up for any ideas from other people.