I ran a prologue for one of players in my 4E game.
She's playing a Storm Sorceror re-skinned into a Frost Sorceress.
I had two NPC characters (a Warforged Fighter and a Druid) join her because I was worried about her ability to survive combat.
She tore waves of zombies apart all on her own. Mostly by being able to outpace them and blast the hell out of them.