Ok Heroes is copying Naruto again, Tracy (Ali Larter) can not only manipulate Cyrokenisis, but she can use Hydrokenisis and liquidize her body when she wants...which means she's invulnerable to weapons and physical attacks OMG, you guys know
Suigetsu from Naruto right...well he could do the same. So I'm thinking Tracy is invincible, unless someone can evaporate her with a lot of heat, OR, hit her with a bunch of electricity techniques to paralyze her (prevent her from being able to liquidize) and then kill her physically.
Btw from last season, reason why Sylar was turned into Nathan was so that it woudln't look like Nathan (a Senator) was murdered (US Government would launch a whole other investigation) and she didn't want Sylar to still be loose and continue his power tripping (mother Petrelli). So she made Matt Parkman use his ability to Persuade (remember he can use
Mind Persuasion Manipulation,
Mind Reading, and
Genjutsu type Illusions on people), which forced Sylar into believe that he is Nathan, and forced Sylar to Transform into Nathan (Remember Sylar had the ability to Shape-Shift, so just a little Persuasion from Matt = bye Sylar hello Nathan).