After playing as Valhalla Surge and against her, it would be impossible to say she doesn't need nerfs. I've spent nearly all of my races as a lv1 and have pulled wins that shouldn't have happened. I'm an average player at best and I'm cruising to 6k on easy mode. That said, I do like her design and kit. Her play style can be very fun, it just needs some balancing.
Berserker's Axes - Axe spam makes it nearly impossible to get and hold any items. Can't see it coming because there's no warning. Can't jump or slide under it either. It's also extremely fast and goes through obstacles. When it's picked up again, the hit box stays in the ground so you hit an invisible axe. (Definitely a bug)
- I think slowing the speed down and not allowing them to go through obstacles could help lessen the spam and axes littering the tracks.
Viking Offense - Entire boost does too much. Very fast, extended duration with lvs, damages player/removes an item, and shields protect from 3 hits. It's also stackable, though I don't know if this is intentional or a bug.
- Maybe slow the boost down when shields are lost, or let it only take one hit like Nutcracker Silver's or Fortune Teller Amy's. Remove the ability to stack if the speed and duration are not going to be reduced. It's very easy to abuse in its current state and is unfair all around.
Thunder Shield Wall - Hit box seems to be a bit wonky and clips you. Moves too fast to reliably dodge. Hits very hard.
- Slowing the movement of the trap could make it more tolerable to deal with. And if not a speed reduction, perhaps a damage reduction instead.