The 'Netherese' element of the Netherese-infused Tadpole is a completely homebrewed Larian invention, so a DM could easily classify it as a 'magical disease, curse, or a similar effect', with emphasis on the 'similar effect' part if all else fails. As for 'both' though, I'm not sure what the tadpole has to do with Reincarnate, unless you are unfamiliar with the spell description - Reincarnate only requires that you die and then it summons your soul itself and implants it in a brand new, magically created body, with the state of your old corpse and all effects on it being completely irrelevant.
Okay, so continuing the role as "Advocatus Diaboli", what exactly is "the state of the old corpse.
Could you kill horned Wyll and resurrect him without horns ? Or is that part of his state ? Could the embedded and netherese magic encased worm be part of the state ?
Omeluum says that the lesions in the brain caused by the worm may be lethal also, and removing it would need special care. So if you resurrect it and the brain is fatally damaged, then that would probably not help.
Again, judging by the questions being asked, it seems like you simply haven't read the text of 'Reincarnate'. Here, I'll just post it:
![[Linked Image from dnd5echaractersheet.com]](https://dnd5echaractersheet.com/wp-content/uploads/2018/05/Reincarnate-5e.png)
Most sentient creatures, particularly playable humanoids, in DND have canonical souls, completely separate from their material forms. When they die, their souls depart the Prime Material to the City of Judgement where they await assignment to the respective plane of their deity or the Wall of the Faithless unless they're yanked back to the Prime by a resurrection spell or mechanism. Reincarnate only requires a piece of a humanoid corpse's to identify its correspondent soul, then it targets the soul itself and implants it in a brand new body. You don't resurrect your old body, you resurrect the soul.
Your brain and head could be thrown into a volcano or into Gale's sphere of destruction, all a druid would need is your fingernail in order to pull your soul back from the planes and recreate a new brain and body for it.
Yes, you could also remove the horns from Wyll, however, you will not annul his contract, that's why Devil contracts are explicitly tied to your soul rather than a body, with the soul being infinitely more valuable due to its naturally eternal existence. So Wyll's soul would come back in the body of some random Halfling or Elf or whatever that lacks the horns, but Mizora would probably just give him a new set of horns.
