[Kameron8]

Greaper does not appear to be applying to non-mage invocations. With rank 3/3 in Greaper, the damage done by Divine Shower did not increase by an additional 30% compared to running with base mage class against a jammer.

Mage/Priest:

Jammer takes 30 Light magical damage.
Jammer takes 30 Light magical damage.
Jammer takes 30 Light magical damage.
Jammer takes 30 Light magical damage.
Jammer takes 30 Light magical damage.
Jammer takes 30 Light magical damage.
Jammer takes 3 Light magical damage.
Total: 183

Evoker/Priest:

Jammer takes 32 Light magical damage.
Jammer takes 32 Light magical damage.
Jammer takes 32 Light magical damage.
Jammer takes 32 Light magical damage.
Jammer takes 32 Light magical damage.
Jammer takes 32 Light magical damage.
Jammer takes 5 Light magical damage.}
Total: 197

14 extra damage is dealt, which is accounted for by the passives 'Evocation' and 'Spiritual Domination'. Greaper is not applying.