Disable them all you want, your team will just get invader smoked by something else. I can invade and wipe a whole team with Aisha's Embrace or Servant Leader. Here's some plausible options to "fix" Gambit. 1. Remove invading all together or have a Gambit Type without invading. 2. Have the option to lock the other teams portal using motes. 3. Don't give the invader wall hacks to see the invaded team's location. 4. Invader acts as a blocker, always spawns at the bank. 5. Remove prime damage phases cause you're literally just putting the breaks on damage while the invader can come in and reset the boss' health.