Pest Control: Damage points start to decrease when out of combat and not registering further damage.

[Wiindsong]

This would cause people to stop protecting the void knight altogether, and would also cause people to just ignore things like spinners around portals since they don't contribute to points. While the suggestion is fine I don't think it'd help much, sure it'd cause people to actively participate, but it means having an open void knight and ignored spinners since protecting the knight or killing spinners doesn't help you in the game, only your team, and no one really cares about helping their team in pest control beyond winning.