First of all, congratulations are in order. I have played competitive magic for about ten years, and I believe that once all the bugs are worked out and the full game is available, I will be hooked on this game. I have a few thoughts, both positive and negative.

The mage needs more card drawing. This is a typical ability of magic users, and will help counteract the resource drain of sacrificing and casting spells, which will deplete the hand too quickly. On that note, the enemy mage's ability is going to be very powerful , as it deals with this effect long term. I believe this hero will be a popular choice.

The game will be very difficult to judge until activated abilities are useable. The hero's ability is what it is judged by, and 'testing' the mage, or any other hero, is pointless without fixing this. The lack of abilities also handicaps the deck, as the opponent mage has access to cheaper more powerful allies, and your main kill spell, the mage's ability, is unuseable. Other than this, I have only really dealt with known bugs and issues.

You seem to have developed a naturally intuitive game that has the potential for lots of depth and a high level of complexity. Keep up the good work.