this seems broken. just play an instant during each player upkeep, and they cant play anything else that run except things that respond to it. i guess you'll run out of instant eventually, but still, seems a bit to powerful to me :/

It's a lot of hoops to jump through, so I don't think being locked is a real issue. If anything it might be a bit too good at giving you extra value out of lightning bolts, but you're still playing an otherwise blank creature to do so.

Too good a sideboard card vs control?

Nothing can ever be countered (by spells) since declaring you are casting the spell is all it takes to cast a spell (no resolution required)

Even then it still hoses a great many combat tricks, of any colour, esp. from the defending player.