The video above outlines a fundamental problem with this game mode. I already know that all of the "Wither Assault mains" will bash me for even mentioning this, but clearly this is not fair for the wither team in any way whatsoever. I've seen this happen dozens of times and it is just boring to witness one team do this to ensure they get their wins. The game, like any game, should be competitive and promote some sort of difficulty for both sides. However, this sort of thing really only happens when a group of coordinated players (who each know this method) come together; so it only applies for those games really. I don't want to be that guy that ruins the fun for them but if you take a look at the chat in the video, it's pretty clear that the game is one sided. The best solution that I can think of is to simply add a cooldown to using the revival potions; not much more I can say to that.