I went 12 8 14 and carried hard as Sivir Luna getting only E and W. Still lost sadly, but it was more of a team comp thing.
She does make a good hard carry, but part of her kit is having a nuke, and being able to stop people from Town Portaling out with it, along with offering a better burst early, carry later with autoattack option.
Also, why do you keep calling her Sivir? I think Luna's around seven years old now, with only minor changes to her kit over the years. At least, the only change in my memory is that her damage aura passive also grants her night vision now, but that could've been done a while ago, as I haven't played the original DotA in a few years now.
Fakeedit: Oh, and the damage bonus is now flat instead of a percentage? It used to be a similar effect to Drow's ranged aura, but I think it does give a bit better returns early on. You still don't want to get the W too early, though. It'll push the lane too much at a time that you either want to be in a safer position ricing the lane (autoattacking/denying your creeps once they get below half health in order to keep your lane at a distance you choose) so that you don't get ganked as easily.
And I can carry with pugna.
Yeah, Pugna is amazingly awesome, as long as they don't have a stun of some sort. Push lanes like crazy, make other nukers do more than full damage with spells, and rape other mages with ease. Then get an Aghanims, and enjoy the 300 damage per second, 0 second cooldown ultimate.