Is Tenacity legal in Standard, Modern, and Commander?

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

Tenacity

Q: What type of card is Tenacity?

Tenacity is an Instant. Its oracle text reads: "Creatures you control get +1/+1 and gain lifelink until end of turn. Untap those creatures. (Damage dealt by those creatures also causes you to gain that much life.)"

Instant

Creatures you control get +1/+1 and gain lifelink until end of turn. Untap those creatures. (Damage dealt by those creatures also causes you to gain that much life.)

Set Shadows over Innistrad

Rarity Uncommon

Mana Value 4

Artist Zoltan Boros

Collector # 42

Scryfall Gatherer