Is Rhox legal in Standard, Modern, and Commander?

Rhox is legal in: Modern, Legacy, Vintage, Commander.

What type of card is Rhox?

Rhox is a Creature — Rhino Beast. Its oracle text reads: "You may have this creature assign its combat damage as though it weren't blocked. {2}{G}: Regenerate this creature. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)"

Rhox

Creature — Rhino Beast

You may have this creature assign its combat damage as though it weren't blocked.

: Regenerate this creature. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)