This sounds good, but it gives away when baron is dead.
If the enemy team hasn't seen him die or doesn't know baron is dead, then they'll think he's alive. BUT!!!, if you can see the land changing, "Oh, barons dead, someone time it like the good ol' days."
It's a nice idea honestly, but if they (IE, Riot) doesn't want people to see dragons animation over the wall, I doubt they'd want to give everyone an enormous warning that damages or heals half the map, signifying that he's dead or alive.
IMO, it would irritate me if I could baron without it being obvious that we just did it. They'd either want a piece of us because we might be low ATM or start running from the can of major buttwhoopin' we're about to crack open on dem foolz.
I will say though, having everything nice n happy at first is nice, but then at the 15 minute mark, shockwave, minor shaking (earthquake action op) and the cracks n such appearing, hell maybe even baron could roar as the announcer says "Baron Nashor has entered the Fields of Justice!", would be pretty damn sick. Just everything has to stay fawked up cuz showing baron coming and going is too much.