When spectating, it could be a nice addition, to use the cooldown display for the aegis, but count down the time it takes until it gets reclaimed by roshan. You can check the roshan spectator counter, but especially in teamfights, where every second until rosh reclaim counts, it would mean a huge improvement at no costs. Especially since the system is already in place.

To clarify: Countdown should only be visible to spectators/broadcasters, not for the players.