Dear Frogboy please have GPG remove this change! I have said it before and I think most of the experienced players will agree that Horn of Battle is already very useful as it is if properly used. Minion Erebus with HoB is extremely powerful and 10 seconds of near immortality for Nightwalkers is more than enough! You can easily take down a tower.
I assume the cooldown of 45 seconds for HoB hasn't been changed. This means that Erebus' minions are basically unkillable for most Demigods. 25 seconds will not only be enough time to attack a demigod defending a tower but to chase him away and destroy the tower. Only Rook, Regulus and Torchbearer have a chance to kill Erebus minions under the influence of HoB.
I'm afraid this change will make Erebus an unstoppable force and he can just take down one tower after another because his minions are untouchable for more than half of the time!
Please test this change against an experienced minion Erebus player and you will see what I mean. Thanks.