Joking aside.. (more than 10, i can count)... Malp, Annie, Sivir, Cho, Nasus, Kayle, Alistar, twitch, trist, shaco (solo baron can turn the tide if you dont watch for it), Morgana, Corki, Blitz (being able to grab people consistently can change a team fight into 4v5)
However, good teamwork and communication is the best thing to have.
But for real....twitch + kayle
There are plenty of top characters, depending on how you use them but the new flavor of the month which seems to be devastating is Crit twitch ult + kayle invuln. Those 2 can pretty much explode an entire team.
Comment below rating threshold, click here to show it.