So this has been an issue since day one in dominion, it's probably about time you guys n gals at ubi addressed this and I don't think your new incoming perks will be enough to stop 4 players coming in and ganking at spawn. Something along the lines of a bleed effect applied to the health of the offending party at the spawn location should suffice
I’d prefer a damage and defence debuff to be placed on opponents who cross a certain threshold into friendly spawn area.
But this starts an issue where the enemy team who is breaking would just run into their spawn and hide there. This would make the end game stale and turn it into a Mexican stand off, or who can get lucky with a catapult or bomb.