Core/Spells: Fix Ebon Plague and Wandering Plague

Ebon Plague fix by @Unholychick
Wandering Plague fix by @tobmaps
Ref: #12314
Closes: #1818

Core/Spells: Ebon Plague correction.
Thanks to @maxxx
Merge branch 'master' of https://github.com/Exodius/TrinityCore