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.
Heal: early game you can get caught out by other melee dps champs always helps to get away to your turret. Heal is also great for when your low on health your dps will be amazing but sometimes ya just need a lil more health to chop down that last champ.
Flash: Well its obvious being at low health most the game you can be focused and caught out always great to have a back up plan :P
Use undertow to harass in lane and farm minions. do not intend to get 1st blood as you will find yourself giving them 1st blood. Once you have got your first Zeal you can start to really pwn.
Stick with someone who has a slow eg. Ashe as she is slows them gives you great opportunity to chop them down this works great for tanks.
By now you should have both your Phantom Dancers, you should really see why this works so well. Once you got an Infinity Edge all hell brakes loose you can kill the whole enemy team at once and if the game goes on for a while like some do i often replace the boots with another Phantom Dancer just for giggles.
let me know what ya think.
Have fun =D