One suggestion to balance the Wall of Illusion would be if it only reflected damage actually inflicted by the opponent's cards. That way it simply doesn't get abused as Yellow Cake by anyone lucky enough to score Armageddon or Stone Rain.
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Another card that could use some balance point as well is the Phoenix. Now I understand this is only a beta so things could change, but as is with 10 Fire in your pool they are even immune to creature control. Now theoretically direct damage cards would be a way to get around them, but if the player has lucked out with Healing spells then the end game will eventually lean in favor towards whoever has the most Phoenix out as they can simply raise their life points out of the range of your biggest direct damage spells and if they actually play Armageddon or Stone Rain with a full flight of Phoenix out they simply deserve to lose.
My suggestion would be if the Phoenix subtracted a certain amount of Fire mana as a regeneration cost (somewhere from 3-5) instead of the 10 minimum, that way it would limit the abusability and curtail the inevitable Armageddon buildup that a whole squadron of Phoenix would involve.