Can someone tell why was I hit with 350 damage with nothing by a Yi?

I was playing game of One For All. Their team was a team of Yi and we were a team of Vayne . I died due to him diving me but after he was dead i was hit with 350 damage .01 secs after he died and before my rune gave me health. I looked at my death recap and there was a blank box with 350 dmg and it says 14% of the total damage dealt to me. Can someone explain why I randomly took this damage from nothing???