Is Intrepid Adversary legal in Standard, Modern, and Commander?

Intrepid Adversary is legal in: Modern, Pioneer, Legacy, Vintage, Commander, Historic.

Intrepid Adversary

Q: What type of card is Intrepid Adversary?

Intrepid Adversary is a Creature — Human Scout. Its oracle text reads: "Lifelink When this creature enters, you may pay {1}{W} any number of times. When you pay this cost one or more times, put that many valor counters on this creature. Creatures you control get +1/+1 for each valor counter on this creature."