The Tentacled One
Maybe Blake Rasmussen should consult Sam Stoddard about this idea.For Mythic Championship II in London, we're going to be trying out a new mulligan rule that we have been playtesting internally for some time. We believe the new rule smooths out opening hand decisions even more, though it certainly has some implications for formats like Modern.
The rule we'll be testing in London is as such: When you mulligan for the Nth time, you draw seven cards, then put N cards on the bottom of your library in any order.
So, for example, let's say you're taking your second mulligan of a game, what we often call a mulligan to five. You would draw seven cards, select two, and place those two on the bottom of your library in any order. Then you would decide whether to keep or mulligan again.
While we have been testing this mulligan rule internally for a while, we are treating this tournament as a test. Once our game designers have reviewed the tournament, spoken to players, and looked at the data, we'll decide whether to implement the mulligan rule wider.
7-7-7 (Shuffle x Back)
This was attempting to do something similar to the scry mulligan we used at Pro Tour Magic Origins, but in a way that was more powerful. Basically, each time you mulligan you draw up to seven, but get rid of cards that you can't use (down to the appropriate smaller hand size per mulligan), thereby increasing the chances that you will have a reasonable hand.
What we liked: This seemed pretty close to right power level for Limited, but had some problems. You generally ended up shuffling your most expensive card back, but if it wasn't obvious, then the decision on which to shuffle back was pretty hard—and made this take a lot longer than a regular mulligan.
What we didn't like: This mulligan was way too strong in Constructed, and encouraged big changes in deck building. Perhaps the most notable thing was in Modern and Eternal formats, where sideboard hate got a lot stronger since you could shuffle extra copies back into your decks. Similarly, combo decks got a huge advantage since they could mulligan away possibly useless cards. In one of our biggest rules violations for changing the mulligan rule, it clearly changed the parameters for deck building, and would have a profound impact on how older formats played out.