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.
This is only a build.
In order for this build to work:
-You need to be good at last hitting with Q
-You need to be good at juking people with your stun.
-You need good positioning
-You need to execute 5 things in a short time window.
This build provides:
-Great early game assistance for your Baleful Strike
-Extreme damage late-game
-Good survival with high movement speed and a banshee's.
-The ability to blow up anything with AP or high HP. Some casters such as Vlad have both.
-Extreme movement speed for a caster. This will help a lot with juking enemies around a tower with your stun on them. And avoid being ganked.
You get CDR boots with Fiendish Codex so early because you MUST farm your Q. That's also why one Quintessence gives you extra Mp5.
A good estimate on how much +ability power from your Q is:
-5 minutes, +5
-10 minutes, +15
-15 minutes, +45
-20 minutes, +135