Oh, now I see why he put his armor on! Looks like transformation shenanigans are afoot!

On a side note, 'Ni no Kuni: Wrath of the White Witch' introduced many spells that the player is able to cast, and a bunch that they can't, including, but not limited to, the ability to turn into a werecat or a werefish. So a wereboar spell doesn't seem like it would be too far out there, and Marcassin has demonstrated having magical ability on par with Oliver, if not greater, so why shouldn't he be able to cast such a spell?

The artwork was done by  ConnerCoon, and the submission in his gallery can be reached via the link below:

https://www.furaffinity.net/view/34664867/

Marcassin belongs to Level 5 and Studio Ghibli.