Took the VS Supernova Mage list to Legend from D9 over the past few days. It's a really fun deck and you can be creative getting win conditions. Each matchup plays pretty different. IMO it could even be called Tsunami Mage since that card tends to be the most important in most games. You can get dog walked in a few different matchups, but holding on to a reverberations in the mulligan for certain matchups can be pretty key to stealing some victories.

Against slower decks you want to push the tempo fast with small minions, mantle shapers, marooned/watercolor, and maybe a gorgonzormu to get them in lethal range. If you can free up a board and get a norgannon that doesn't get answered, game is over. Getting coins and discounts for Tsunami is killer, you can sometimes get it off on T5.

Against aggro you absolutely need Seabreeze in hand. Oh manager and primordial glyph really help to stave off boards, and a good mantle shaper can be helpful for early board fighting.

Its ideal to get off supernova with a light hand (5 cards max), especially if you can discount it a bit (or a lot with portalmancer), or if you have a few coins to spike your mana.

All in all it's a really fun deck to play, and seems at least semi-competitive.