As I see it, it can completely shut down decks based on buffing (such as buffed chargers) and likely a lot of other decks. This would really buff Rain of Fire and other non-targeted effects. Seems extremely powerful as long as you make sure to keep targeting things out of your deck.
If you have more creatures than your opponent, it's unwise for them to buff their creatures. Maybe you could make it a 75% or something chance of the target being randomized so it isn't such a heavy lockdown alongside creature spam?
I like it. Really kills , though. That's good, mono- is very powerful, even FG killing.
How does it shut down mono-aether? Immaterial should give them an advantage against this in general.