Is Chancellor of the Annex legal in Standard, Modern, and Commander?

Chancellor of the Annex is legal in: Modern, Legacy, Vintage, Commander.

Chancellor of the Annex

Q: What type of card is Chancellor of the Annex?

Chancellor of the Annex is a Creature — Phyrexian Angel. Its oracle text reads: "You may reveal this card from your opening hand. If you do, when each opponent casts their first spell of the game, counter that spell unless that player pays {1}. Flying Whenever an opponent casts a spell, counter it unless that player pays {1}."

Creature — Phyrexian Angel

You may reveal this card from your opening hand. If you do, when each opponent casts their first spell of the game, counter that spell unless that player pays .