Not Updated For Current Season
This is the build i prefer to use for this charater it provides alot of AP so you can pull out alot of damage from the bombs you place on the enemy. Also if you have a tank who is going for a push in a 5vs5 team battle putting Chrono Shift onto a team mate or on your self will end up giving you nearly all your health back or restoring it to full again. making your team last longer giving you the edge on the team battle. This build is best played in a lane with a dps or a tank.
The summoner spells i chose are the ones i useualy pcik for when i play a mana user who can die very quickly i use ghost becuase it help alot to get away from a enemy or chase up onto one. i also chose Clarity becuase in early game it gives you the edge to push them a bit more and chip away at there helth without having to stay still for a while and wate for your mana to regen. There not esential so pick what summon spells you would prefer.
when it comes to picking items it not nessary that you follow the order but that order is what i like to use having Mejai's soulstealer as soon as i can after so those early on game kills and ganks will help you to get other items to pull out insne damge. but you should keep to the items for end game becuase the damage out put at end level and being able to reivie a team mate to full health in the heat or a 5vs5 after he got killed is very helpful.