This is pretty much just for my own personal reference, if you wanna try it out, here's a basic guide (really basic)

early game: Farm minions till you have Rod of Ages (auto attack till minions are roughly 1/4-1/3 hp then Disintegrate to kill them, get money and not spend mana), do not try and rush to kill the enemy, you are squishy and will die.
mid game: keep farming minions but help others push turrets
late game: by now you should have Will of the Ancients and should start working on your Archangel's (for some extra late game mana). At this point you should be watching your stun stacks and if a team fight happens or you need to rush a turret, use Summon: Tibers to either stun their whole team, or have some extra dps to bring the turret down faster (it also helps if you need to pull aggro off turret for someone to chase past turret).

If the game lasts long enough to get your Archangel's Staff (and maybe Deathcap), then you can easily just run in, summon Tibers and kill everything.

If you decide to try this out, please rate.

credit: http://leaguecraft.com/strategies/guide/2685-annie-all-rape-no-vaseline.xhtml
(some items have been changed for my personal preference.)