You can see her regardless of having an Oracles. And no, it's not the same as Akali and Shrooms. Akali has her shroud, wich is a limited area of stealth - an area wich the opponents can see, making it quite fair. Whereas Eve (Rengar and Twitch aswell) can go stealth and fuck off (Eve not so much, but she has ridiculous MS making Oracles pointless). A good Eve (again, see the IPL tourney, how Alex Ich plays her, and the others who played her) will just BANK AROUND the enemy team, coming from behind after the fight's already started.