"You may instead". Otherwise, it's a bit hazy if you could keep doing it. I mean, most people should be able to figure out that you don't win on turn 0 with this, but, you know...

I do find it funny, the times you can use this with benefit for you and your teammate. "Man... you got to mulligain to 5? Screw it. Let's just keep mulligaining. I'm bound to draw one of my four dragons sometime out of 15 cards I can possibly mulligan for." :o

I basically took the wording from Serum Powder, which doesn't use "instead," so I didn't think this needed to do so, either.

I really like this for pretty much exactly this reason. It's a card useful enough to include at least 3x in your deck, but it's protection against the case where you have to mulligan down to 5 or lower. Of course, it'll really suck if you got down to 1 and didn't find this!

I assume that if you mulligan to 4, then find this and use it, and then mulligan again, you go to 5 not 3?

I also wonder if this needs to say something like "All players may now continue mulliganing", because I think in some formats people do their mulligans separately, so if P2 uses one of these after P1 declares no mulligans, it's not clear if P1 gets to mulligan on their new hand.

It's the intent to allow continued mulliganing, so I'll add that for clarity.