Plague should have no cooldown / slowdown if not charging the power for long enough
There is a minimum threshold that you need to pass for your power to actually do anything (= for vomit to come out). It is possible to charge the power for a little bit and for nothing to happen then, except for the cooldown / slowdown after using the power to trigger.
There should be no slowdown if you do not reach this threshold or there should always be vomit, even if it's only a bit.
Comments
I have just checked it on the live version of the game (4.2.0) and this happens for both Vile Purge (green vomit) and Corrupt Purge (red vomit). It should happen for neither.
An alternative solution is to force the charging until the minimum charge level is reached.
It should just not be a thing honestly. Doesn't make sense you can partial charge for no effect. Or have some kind of indication that you've reached a high enough charge.
It also shouldn't happen after not vomiting.