Mordekaiser W bugged (on some maps?)

Description: Mordekaiser only receives full xp for a creep in a duo lane on twisted treeline (and possibly ARAM, more testing needed) if he kills the minion with his w damage. Steps to reproduce: enter a twisted treeline (or ARAM?) game with mordekaiser and another champion, last hit with both champions in xp range, only receive reduced xp. Expected result: mordekaiser receives full xp for creeps he last hits Observed result: morderkaiser receives reduced xp Reproduction rate: 10/10 TT, ?/10 ARAM