When I needed 3s during the transition, the buy in oriented “No Holds Barred” event was great because I was guaranteed a 3 token. I needed enough of them that it was worth it to pay the 150 hp to join.
Now that we are fully entrenched in the 4* transition I think it would be fun for another go around with this with a 300 HP “buy-in”. (double the cover cost, double the buy in)