Attack on Titan Season 3 is one of the best series ever released but it left all the anime lovers with suspense about the rod reiss titan form. But we have gone deep down in the list and found the real truth. Well, It could be a combination of factors. The serum Reiss drank was created for Historia. Instead of injecting the serum into his bloodstream, he licked it off the floor. He wasn't ingesting the entire dose of serum, but rather a small portion of it. He is a member of the Reiss Royal Family, which implies he may have a bloodline that produces unique Titans.