Is Rakdos Riteknife legal in Standard, Modern, and Commander?

Rakdos Riteknife is legal in: Modern, Legacy, Vintage, Commander.

Rakdos Riteknife

Q: What type of card is Rakdos Riteknife?

Rakdos Riteknife is an Artifact — Equipment. Its oracle text reads: "Equipped creature gets +1/+0 for each blood counter on this Equipment and has "{T}, Sacrifice a creature: Put a blood counter on Rakdos Riteknife." {B}{R}, Sacrifice this Equipment: Target player sacrifices a permanent of their choice for each blood counter on this Equipment. Equip {2}"