Why was Merged Zamasu losing his immortality?

[dragonballgeek]

Personally, I don't really buy the whole Merged Zamasu losing his immortality because of a mortal body clashing with it. If that was the case, then why wasn't Future Zamasu's immortality clashing with his mortality? I mean, Future Zamasu was once mortal and has to wish for his immortality. I know one person will say that the writers wrote themselves into a corner by having an immortal antagonist that would be literally impossible to beat and the immortality had to be nerfed due to plot convenience, but they had the Mafuba which they could use to seal Zamasu.

Half immortal. Half mortal.

While they destroyed his mortal body, his immortal spirit still remained. I think that's a fair ending.

Which I question. How can one be half immortal? You either immortal or not.

What's hard to understand?

Since he merged with a mortal, something had to be affected, and it was his flesh. This is why after Trunks disintegrated Zamasus body, his spirit still remained.

[Merged Zamasu]

Half immortal. Half mortal.

While they destroyed his mortal body, his immortal spirit still remained. I think that's a fair ending.

Which I question. How can one be half immortal? You either immortal or not.

What's hard to understand?

Since he merged with a mortal, something had to be affected, and it was his flesh. This is why after Trunks disintegrated Zamasus body, his spirit still remained.

Small correction, Trunks didn't disintegrate Zamasu's body

Trunks only sliced Merged Zamasu in half. Remember half of Zamasu was still immortal, there was no way that simply slicing him in half would cause his destruction. Zamasu self-destructed, like Vegeta did in the Buu saga, because he kept talking after Trunks had already sliced him in half, and his body was obliterated only after Zamasu had finished to talk. Furthermore, Gowasu stated "He's cast off his form as a God, and is trying to become justice and order itself". To "Cast off something" means to "Give up something". So Trunks only sliced Zamasu in half, it was Zamasu who willingly destroyed his own body so that his true potential could be unleashed.