About that "most powerful thing in the multiverse" part. The collector has dealt with beings that claim to be the most powerful being and... Let's just say it didn't end well for them
The collector won't challenge inkmatas if inkmatas doesn't challenge the collector
So the idea is similar to the dungeon guardian he has a defense mode which reduces all damage to 1 to him but when exiting defense he has a damage reflection attack that sends out the unreduced damage