It makes the mage hero power scary. Let me ask you this. Is it fun for a player to worry about an infinite value effect that is always available from the start of the game? Hero powers suck and cards that assist them suck even more. You want it to be something that allows a player to do something so they don't feel awful when they are out of cards? Fine, but don't make them a central game play mechanic when by design they are non-interactive.
I think this is too slow for card draws and I'm not sure why you would put this in Odd Mage. Why not just play Black Cat? For one stat of health less, you get Spell Damage +1 AND the drawn card immediately. It can be played on turn three without risk. With this, you basically are playing a vanilla 3/4, hope it doesn't die, and then you're spending an extra two mana to draw a card. provided your opponent has a minion with 1-2 health on the board (depending on if you're using Baku or not).
As a 3 Mana 3/4, it's pretty much automatically at playable status. If it draws you a single card or more, it's immediately bumped to very good. That doesn't seem like that should be hard for most mages but it's not a guarantee. I'm thinking somewhere between playable and very good right now.