This time I an messing around with the paintbrush, and found Ink Sling an interesting and useful ability. But sadly, it isn't efficent enough to be used in combat (for example: dealing with illager raids) or massive creature/block coloring. Maybe there can be 2 upgraded version of Ink Sling, one is mainly for combat, efficent and powerful, and the other one is mainly for creature dying, with massive effect area and little/no damage to creatures?
Maybe this feature can make the paintbrush more useful!

And I've got several ideas when watching my dad playing Hollow Knight: Maybe there can be a modular upgrade, that use the paintbrush to draw a random line in the air, and shoot a line of mutiple ink bullets that either harm the mobs, or paint the blocks, on hit. Maybe an enchantment can allow the paintbrush to be used as a sword, dying the mob on hit. Those are inspired by the bossfight against Theo, who also uses a paintbrush as a weapon.
(Those came into my mind when I see the black statue which looks like a character in Hollow Knight)
...or maybe, an enchantment can make the paintbrush get the ink of a colored block or mob's color, and turn them into their unpainted versions? All in all, the paintbrush can be functionally interesting,but if there should be many abilities on one 'brush, you'd better to make an easy-to-use ability selection interface.
(PS: I'm never short of thoughts, but sadly I can't do any programming job except some simple Python programming)

It will get a lot more use and variation once modular spells are in ✅
Leaving this open to collect all suggestions regarding that.