So i was playing a match and i hit the jett for 154. Isn't the max damage 150 ? Also sometimes it shows I gave 300 damage. So what does it mean?

I recently got into watching the tournaments and would like to be able to follow what's happening better. Casters and analysts during Lock/In repeatedly referred to Haven as an IGL playground. Can anyone explain why? And what other maps are...

I was wondering what the dps of each molly is in game. KJ swarms, Brimstones incendiary Y, Phoenix hot hands, Vipers snake bite. Thank you for your time