Is Will of the Naga legal in Standard, Modern, and Commander?

Will of the Naga is legal in: Modern, Pioneer, Legacy, Vintage, Commander, Pauper.

What type of card is Will of the Naga?

Will of the Naga is an Instant. Its oracle text reads: "Delve (Each card you exile from your graveyard while casting this spell pays for {1}.) Tap up to two target creatures. Those creatures don't untap during their controller's next untap step. *The charm of a naga is undeniable.*"