[Gameplay] True Damage

I'm not entirely sure how this happened or how to recreate it. After finishing this match and going to look at the damage dealt to champions, Yorick had somehow gotten an absurdly large damage to champions result. According to the match data he dealt 400,000 true damage to champions. Again, I don't know how this happened, or how to recreate it, but if anyone else has an explanation I'm more than willing to hear it. For the record, this was a custom game played among friends.