Is Caustic Exhale legal in Standard, Modern, and Commander?

Caustic Exhale is legal in: Standard, Modern, Pioneer, Legacy, Vintage, Commander, Pauper, Historic.

What type of card is Caustic Exhale?

Caustic Exhale is an Instant. Its oracle text reads: "As an additional cost to cast this spell, behold a Dragon or pay {1}. (To behold a Dragon, choose a Dragon you control or reveal a Dragon card from your hand.) Target creature gets -3/-3 until end of turn."

Caustic Exhale

Instant

As an additional cost to cast this spell, behold a Dragon or pay . (To behold a Dragon, choose a Dragon you control or reveal a Dragon card from your hand.)