Is Sworn Defender legal in Standard, Modern, and Commander?

Sworn Defender is legal in: Legacy, Vintage, Commander.

Sworn Defender

Q: What type of card is Sworn Defender?

Sworn Defender is a Creature — Human Knight. Its oracle text reads: "{1}: Sworn Defender's power becomes the toughness of target creature blocking or being blocked by Sworn Defender minus 1 until end of turn, and Sworn Defender's toughness becomes 1 plus the power of that creature until end of turn."

Creature — Human Knight

: Sworn Defender's power becomes the toughness of target creature blocking or being blocked by Sworn Defender minus 1 until end of turn, and Sworn Defender's toughness becomes 1 plus the power of that creature until end of turn.