Be Veigar,

have a 1500 magic damage ult once your opponent is at 1/3 of his health. Now be Pyke, have a telporting AOE ult wich kills everyone once they reach a flat amount of health , your ult ingores shields, your ult resets for 20 seconds upon every other kill, your ult can also be used as a skillshot, has immense range , and can only be dodged if you have flash or a mobility spell wich can get you out instantly while also having the range to get out .