I understand how gem grab isn’t working for you, as randoms suck. And the find a team feature doesn’t work at that trophies because it’ll match you with 500 team mates. I recommend doing duo showdown with tick
Instead, it should be a 5v5, and a 50,000 health boss on each side. It would be similar to heist, but back in early beta, heist was like you said, with one side defending and one side defending. Then they changed it, so that would most likely happen here too.
Another thing they could do it make it 5v5, 50,000 health boss, and keep it the way you said it would be otherwise, but one huge difference: it would be a ticketed event. 30 tokens per win, 15 per loss. It should be 5v5 so you can play with friends. And I feel 20,000 health is way to small, as a simple team wipe could end the game.