Stats

Armor, magic resist, mana and attack speed are the same at every star level.

Rhaast

1 star: Gain 20% Durability for 1 seconds, healing ? over the duration. Afterwards, slash forward in a line, dealing 400 physical damage to enemies hit and knocking them up for 1 second.
2 star: Gain 20% Durability for 1 seconds, healing ? over the duration. Afterwards, slash forward in a line, dealing 600 physical damage to enemies hit and knocking them up for 1 second.
3 star: Gain 20% Durability for 1 seconds, healing ? over the duration. Afterwards, slash forward in a line, dealing 1000 physical damage to enemies hit and knocking them up for 1 second.