Is Coalition Honor Guard legal in Standard, Modern, and Commander?

Coalition Honor Guard is legal in: Legacy, Vintage, Commander, Pauper.

Coalition Honor Guard

Q: What type of card is Coalition Honor Guard?

Coalition Honor Guard is a Creature — Human Flagbearer. Its oracle text reads: "While an opponent is choosing targets as part of casting a spell they control or activating an ability they control, that player must choose at least one Flagbearer on the battlefield if able."

Creature — Human Flagbearer

While an opponent is choosing targets as part of casting a spell they control or activating an ability they control, that player must choose at least one Flagbearer on the battlefield if able.

Set Eternal Masters

Rarity Common

Mana Value 4

Artist Eric Peterson

Collector # 6

Scryfall Gatherer