Shroud is a new name for an existing ability. Shroud was first seen in Future Sight.
From the Comprehensive Rules
- 502.36. Shroud
- 502.36a Shroud is a static ability. "Shroud" means "This permanent or player can't be the target of spells or abilities."
- 502.36b Multiple instances of shroud on the same permanent or player are redundant.
- All older cards with this ability will be receiving errata to change that ability to shroud.
- Cards with variants of this ability, such as "[This creature] can't be that target of spells or abilities your opponents control," will not be getting errata.
- Some cards, such as the Onslaught's True Believer, grant shroud to players.