It suddenly makes expensive creatures with ETB or attack triggers viable
The "morph five mana" rule says that if you attack with your morph creature into an opponent's morph creature, it will take a minimum of five mana for their morph to "eat" your morph (meaning it turns face up and destroys your creature without itself being destroyed)
For example, Nibelheim Aflame can have a white creature deal damage to a creature with protection from red
As such, my attacker gets destroyed before it can deal its own damage and, thus, kill its blocker
If you can deal 21 or more combat damage with your Commander, over any number of turns, your opponent loses the game
One of each without a bundle is $420, which is a 5% saving