Thats good, but it also reads, Whenever you cast a spell, each opponent reveals cards from the top of their library until they reveal a land card, then puts those cards into their graveyard. Being able to cast any spell and then mill everyone is absurd, and the fact that this can then also kill people if needs be is unparalleled
You would be able to easily answer at least the first question
Can I Turn Off Double Strike
As your saga commander, Atraxa, Praetors' Voice was that kid who stayed up too late reading books rather than playing video games in high school (I was guilty of both, personally)
And when card draw and your mana meet up mid-game, are you going to cast two or three spells per turn or just one and pay the tax
If the target creature is an illegal target when Waltz of Rage tries to resolve, it won't resolve and none of its effects will happen