Change Nidhoggur Shadow MVP stats/skillset

[Aaronock]

Actually Nidhoggur should be changed to its official version along with the other monsters there since its pretty much possible now to probably put the whole dungeon into its intended instance form.

I thought we tended to try putting in official stuff where possible once we're able to have it? Isn't that why Nameless Abbey eventually had to be quested to gain access? Or Moscovia being the same?

I'm just applying similar logic to Nid.