Thanks very much for trying the game out and the feedback!
Aha yes, the Light is the Aether elementactually but it just has thelaser right now. Full version of Aether is done, will be in the next update. You can create mirrors to deflect the light and create black holes with it.
Water is currently the black sheep, It should be the most diverse element changing between ice and regular water but it's currently missing a lot of things right now. It's being worked on now along with Aether and Void.
Sure that's a neat suggestion, I can make ground fire be immune for general Fire Elemental.
Next update will be out very soon, finishing up Void and some clean up and it'll be released in about a week.