Is Sliver Legion legal in Standard, Modern, and Commander?

Sliver Legion is legal in: Modern, Legacy, Vintage, Commander.

Sliver Legion

Q: What type of card is Sliver Legion?

Sliver Legion is a Legendary Creature — Sliver. Its oracle text reads: "All Sliver creatures get +1/+1 for each other Sliver on the battlefield. *Hidden within the clicking, chittering swarm is a unique mind, still young, but growing more aware as time passes.* Power/Toughness: 7/7"