Is Shellshock legal in Standard, Modern, and Commander?

Shellshock is legal in: Legacy, Vintage, Commander.

Shellshock

Q: What type of card is Shellshock?

Shellshock is an Instant. Its oracle text reads: "For each opponent, choose up to one target creature that player controls. Shellshock deals X damage to each of those creatures. You create a Mutagen token for each creature dealt damage this way. (They're artifacts with "{1}, {T}, Sacrifice this token: Put a +1/+1 counter on target creature. Activate only as a sorcery.")"

Instant

For each opponent, choose up to one target creature that player controls. Shellshock deals X damage to each of those creatures. You create a Mutagen token for each creature dealt damage this way. (They're artifacts with ", , Sacrifice this token: Put a +1/+1 counter on target creature. Activate only as a sorcery.")