mulligan entire hand at start of game
I know this has been brought up before, but I think now we need this even more now with decisive turns happening by turn 3 or 4 in many games. Having to use even 1 turn to draw usable cards can mean a huge set back. Besides the current meta, it will cut down on RNG games where 1 player just opens up with a better hand.
I think it should the entire hand that is returned so that the players are not trying for god hands, but getting rid of dead hands if they draw it. It could be shuffled back then drawn again, or put at the bottom of the deck then draw.