I think advantage is pretty nice (so I agree with you on the potential power) but it is highly dependent on whether the DM always calls for a wild surge when the rules say he "can." He might call for a roll or surge always, sometimes, or never.
True. However, just like you yourself say...:
Personally, what I'm doing with my wild mage players is asking them to choose a percentage between 0% and 100% at character creation. Whenever it says the "DM can" have them roll, percentile dice determine whether or not I do. (I'm ruling it that if they don't get a surge on their first spell after gaining advantage, they keep rolling the percentage each time until they get it). 50% will be my default. Starting up a new campaign that includes a wild mage on Friday, so we'll see how it works in practice.
This is exactly it, and I believe the PHB would have been better off telling DMs to have this discussion
beforehand.
My belief is that the Wild Mage is balanced on the assumption of "100%"
using your own method. Actually, I hope it is, because the extreme cases are the ones you need to playtest and balance.
In other words, I would answer 100%, and then, if the DM isn't cool with that, choose the other subclass for that campaign.
Allowing the player to set the percentage is great, but not all DMs will be as accommodating as you. Assuming 50% is okay, as long as the player is told this
and is allowed to react by saying "no thank you".
Heck, even saying "no surges in my game" is fine, as long as the DM makes this clear before the player makes his class choice.
Remember that Tide of Chaos is almost everything the Wild Mage subclass has going for it, so without getting back that advantage over and over again, I'd say the subclass is the weakest there is.
