I really like the idea. Beams for a tower defense is super cool and then combining them was also great. However, the icons and UI really don't communicate much to the player. The play button and the buy button should be on opposite corners since you have one corner free. And the buy button looks like a play button. While the elemental beams are cool, because the enemies are generally abstract, the player has no way to use that information effectively. With some more work, I think this could be INCREDIBLE but as it is, it needs on helping the player understand what is going on. It's like if Spellbreak was a tower defense.