The mechanic is fine as it is.
The mechanic needs some work.
Gambit is all about timing, if your timing is bad, you’ll lose, if you time things right, you’ll win most matches, it’s all about summoning your primeval asap and invading at the most opportune moment, and waiting for the right number of primeval stacks before you touch the boss.
I invaded a team that didnt have the the boss up yet, killed all players, when i came back to finish off prime, the other team slayed their prime! Now how the hell does something like that happen? I for one like the game mode but it seriously has several major issues. Its time to put this game on ice again! Back to the filing cabnet with you destiny. Oddysey will keep me busy for a long time
Honestly I think it just needs minor tweaks. Because it is still a risk to try and exploit this. Because what if the other team holds their supers and heavy until they get the slayer up. This calculated risk can backfire BAD. But I would say maybe give the team catching up only 75% of the slayer bonus that the other team worked for.