User blog comment:Emptylord/Archived/PBE Patch Notes (Preseason 3)/@comment-4083774-20121128214007/@comment-3974211-20121129194903

So far as I can tell from that thread, the only question they were asking was whether or not Cleave's damage scales with Siphoning Strike; not whether or not Siphoning Strike gets extra damage from Cleave kills.

I'mma log on and test it now.