The Mark of Tzeentch has the following effects:

• It bestows a 6+ ward save upon the bearer. If the model has a ward save from another source then that ward save is instead increased by 1. So, for instance, a Daemon Prince of Tzeentch would have his 5+ ward save increased to a 4+ ward save.

• A Wizard with the Mark of Tzeentch has +1 on his attempts to cast spells.