This effect can be difficult to set up, but Characters that self-damage, like Mr
If your opponents' commanders aren't in play, you'll be left with the only creature
However, because the counters are removed, it is difficult (but not impossible) to make multiple players lose the game from this ability in the same combat phase
These Commander decks look awesome on so many levels
Madam Mim in particular can be trickier for new players, requiring the player to banish one of their own cards to bring out the shapeshifting witch - if you dont plan ahead, you might end up discarding one of the cards you needed
Most instants and sorceries are balanced with the understanding that they likely will just be cast a single time, so being able to cast them multiple times will make them much stronger