Is Mirror-Style Master legal in Standard, Modern, and Commander?

Mirror-Style Master is legal in: Legacy, Vintage, Commander.

Mirror-Style Master

Q: What type of card is Mirror-Style Master?

Mirror-Style Master is a Creature — Human Warrior. Its oracle text reads: "Backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following ability until end of turn.) Whenever this creature attacks, for each attacking modified creature you control, create a tapped and attacking token that's a copy of that creature. Exile those tokens at end of combat. (Equipment, Auras you control, and counters are modifications.)"

Creature — Human Warrior

Backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following ability until end of turn.)

Whenever this creature attacks, for each attacking modified creature you control, create a tapped and attacking token that's a copy of that creature. Exile those tokens at end of combat. (Equipment, Auras you control, and counters are modifications.)

Set March of the Machine Commander

Rarity Rare

Mana Value 6

Artist Chris Rallis

Collector # 32

Scryfall Gatherer