Is Mythos of Vadrok legal in Standard, Modern, and Commander?

Mythos of Vadrok is legal in: Modern, Pioneer, Legacy, Vintage, Commander, Historic.

What type of card is Mythos of Vadrok?

Mythos of Vadrok is a Sorcery. Its oracle text reads: "Mythos of Vadrok deals 5 damage divided as you choose among any number of target creatures and/or planeswalkers. If {W}{U} was spent to cast this spell, until your next turn, those permanents can't attack or block and their activated abilities can't be activated."

Mythos of Vadrok

Sorcery

Mythos of Vadrok deals 5 damage divided as you choose among any number of target creatures and/or planeswalkers. If was spent to cast this spell, until your next turn, those permanents can't attack or block and their activated abilities can't be activated.