Killing training dummies in practice tool (jayce)

its as simple as it sounds I was playing Jayce in practice tool figured id try a few combos... well I got bored started beating around some training dummies then I suddenly got first blood off one and then was able to repeatedly kill them the only thing that could kill or damage them other than myself was fountain as for allied dummies all I can say is they wouldn't be damaged by tower didn't test fountain and could not test me damaging them obviously and last but not least I was able to recreate the results sadly I could not get video or screen shots as it was coming out blurry or laggy but if you test yourself you should be able to re-create it also its good to note the fact that I could not kill the dummies when I had no items

Runes: Lethality reds and quits (24 lethality) Scaling Magic Resist Blues HP Regen Yellows

Masteries 18/12/0 (Taking Fervor as a keystone)

Build: Black Cleaver Duskblade of Drakthar Yommus Ghostblade Boots of Lucidity Mortal Reminder Guardian's Angel