[Gameplay] Poppy Enrage Buff

I was playing a custom game as poppy with a few of my friends yesterday and throughout the game, there were occasions where I received a passive "Enrage". I was curious to what it was since after a bit of hovering none of my items contained this passive. It also gave a noticeable amount of self buff which included lifesteal, spell vamp, and (I think) a few other buffs. It also shared the same icon as the old Surge spell. I was wondering if this was a bug or if it was just a feature included in the game. I forgot to take a screenshot in game, but here's a screen shot of my build path and score. http://puu.sh/maCJu/97c45b5806.jpg