Here's an idea, but first:
The current complaints about Dark Excommunication, henceforth DEx are essentially based on the fact that it more or less completely shuts down certain armies for an extended period of time after the GK player simply hits a button. This aspect of it, and the fact that there is nothing that can be done to mitigate it, as opposed to say, Malignant Blindness or Swift Movement, makes it somewhat overpowered.
To be honest with everyone, I'm inclined to agree that it is, in some ways, OP.
The 15 second duration to me seems a bit much.
However, the goal of this mod is balance, and currently the GK lineup seems rather lame compared to that of many other factions. At the same time, however, skillful play should be rewarded, and as a result, I have an alternative.
DEx should be restructured in a way to allow players with exceptional foresight and decisive mentalities to win engagements or prevent catastrophic damage to their/their allies armies.
My suggestion:
Dark Excommunication | T1
75 Red
Cloud the minds of all enemy units, forcing them into silence and preventing the use of any abilities for 3 seconds. Cooldown 60 seconds.
The huge reduction in Red and CD allows this ability to be popped at regular intervals, but the reduction of the ability nullification being reduced to 3 seconds essentially means that the player's timing needs to be exceptional. Since the window of opportunity is so short, there will be plenty of time for the player on the receiving end to react to it. At the same time, fast play on the part of the GK and his allies will allow them to gain the upper hand. However, the short duration means that it has to be planned ahead of time, which makes this much more like a skillshot than anything else.