Change all the "target all" abilities to "target one" and you instantly have a better balance. Having Aether Hero in any kind of rush would be OP as hell, especially considering the massive attack boost and shield bypass SoW offers. If you could make one creature invulnerable per turn, however, it would be just like a Turquoise Nymph. Same with Light Nymph: one creature per turn would be fine and still strong.
Entropy Hero needs to have one of the two abilities, and if it's the Discord effect it has to be weaker. I suggest scrambling 4, assuming Heroes cannot be brought out very fast. Depending on how fast, it could possibly be scrambling 5-6. Continuing with the assumption that they're not very fast:
Earth, Water, Air, Time and Darkness Heroes are very powerful, mainly their actives. Steal on a stick definitely needs to cost more, especially considering it's strictly superior to the Earth Hero's ability.