Zilean's bombs are a stand out favourite of mine. Always feels good. Additionally a good Veigar chain ending with a meteor landing on their heads is rather good too.
Most globals are rather enjoyable too assuming it feels like some pro sniper shot. Karthus still counts here, he just cheats at the game here. --- GW2 EU - Gandara --> Sir John Brett - Human Thief, Happy Stromgarde - Norn Warrior, Grizzly Ironstrike - Charr Ranger, Flooff - Asura Engineer