To clarify, it's the battlesphere limiting you, not the galvanizer. You can untap them, but you can't retap them into the battlesphere.
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I don't think you can use the galvanizer to untap the myr. When you tap the original myr, battlesphere has already declared it's attack, and that's the only time it can use that ability, so unless you attack twice in the same turn...
Szadek is not Standard. This deck is.