This is my idea for the final boss! Now incase you don't know what is happening... Here we go: This shadow guy who has no soul hires Scratch to defeat some bosses and collect the posters containing their souls. Scratch returns with all of the Posters and asks for a reward for his hard work. The shadow guy says "Nothing!" and Scratch gets mad and doesn't give him the Posters. The shadow guy tries to take them from Scratch but he trips, falls on the Posters, and absorbs the Posters because he has no soul. Finally, he is a mixture of ALL the bosses. So Chomper, if are reading this, please figure out what the mixture of all the bosses look like and the attacks! Cya man!
