2d RPG Game Sprites remake for commercial use

Hello,
I am thinking about making 2d game RPG but unfortunetly I cant find any appropiate for my game enemies sprites.
Can I use sprites of existing games in commercial use if I moodify them for example by changing colors, shape of some body part, hair, some clothes ? In pixel art it’s just about some paint pencil use, but would it be legal?
Because who would prove that I didnt draw it myself just by takking pattern on the sprite?

There isn’t a mathematical expression for copyright infringement, meaning that if someone told you xx.xx% needs to be changed that’s a load of crap and doesn’t prevent a copyright holder from coming after. Certainly and objectively speaking if you changed something enough to ensure it doesn’t look like the original work, but subjectively someone may notice and begin an infringement case.

Point is the safest way is to create it yourself. There are lots of resources out there that you can buy for pennies that you could use as a basis for your work without any infringement.

Find something on http://opengameart.org/ that has a very open license and start your work from there.