Possible Herald Change
The Herald buff is to weak at the moment while Herald itself is to strong in comparison to it. This change should aim at making the buff stronger so that the strength of Herald is justified.
Glimpse of the Void [Additional Effect]: While alone the carrier of the buff get warned [there is an purple arrow next to the health bar of the carrier], if an enemy walks in his direction within 3000 units range. If the enemy walks/looks in his direction for 10 seconds, then the carrier and his team get true sight on the target for 5 seconds [turning back for 5 seconds stops the timer but doesn´t set it on cd -> turning back longer than 5 seconds sets the buff on cd, being in combat for 4 seconds sets the buff on cd]. The buff goes either on a 15 seconds long cooldown after the warning or on a 30 seconds long cooldown after giving true sight on an enemy champion.
Herald´s defensive or offensive stats need to be turned down a little maybe as well, but I think this buff could be enough to make the Herald more attractive. And I think dragon would be still more worth worth than Herald, so it wouldn´t lead to situations were one team does dragon and the other one doesn´t try to fight for it and makes Herald instead to compensate the dragon. Unless you are that much behind that you can´t fight for dragon, but then taking towers still would be a better option.