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.
Key to this build is massive mana with a low feed and long game time. Start cautious as with any low level mage and careful not to die. I have had some amazingly low death game with Kass due to his ability to rift walk away from danger. Until you get to level 6 this is not possible so you have to ware down your enermies with your null sphere which is your best damage output early on. Your secret weapon is your life regen. Outstanding for staying in lane as long as poss to help with EXP. At higher levels with your target of a mana pool above 5k you health regen is faster than a potion and this is indirectly from your masteries with no items directly increasing your health regen. Why so high mana? multiple rift walks need the large reserves to build up a huge hit. Couple this with blue buff from level 11 the later the game goes on this is as nasty (but in my opinion more fun) than a trynd hard carry build. Play safe and enjoy the spoils of late game ownage.