Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
OK; the manamune. at early game it's sometimes difficult to get some gold. the manamune is cheaper than the archangles staff and gives the same ammount of mana. Your Q ability scales off of mana as well as ablity power. So it's nice to have cause you can hit hard for cheap. When you get your frozen heart, it's a great defense item against a whole lot, like the one tower hit you may experience... The manamune is also a little helpful when just auto attacking something. Manamune will stack with archangles staff so you get the archangle staff bonus AP and some AD also. banshee's is also a good defense item with the health, magic resist, MANA (like we're trying to do here) and it's passive. Rabbadon's.. just AP. =) Good luck hope this doesnt suck