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.
I find that Flash and Exhaust are the two best skills to use; why??
1) Flash dodge. flash right before your hit and you dodge the attack (ie poppys wall slam, turrets)
2) the combos you can do with flash + exhaust. (flash dodge, exhaust, S&P, expunge)
3) (ambush, S&P, exhaust, flash, finish s&P or hit more, expunge)
4) Exhaust + DP really limits the ability of an enemy to get away.
5) Flash is also used as an "get out of jail free" card. Example in a situation If you are clearing minions deep in the map (ex. with a risk of gank) stay near bushes. Flash into bushes + Ambush.
I generally go for skills in this order of availability (S&P, Expunge, Ambush, DP)
with a good laning partner (refer 2 early game) or exhaust generally your S&P or poisons stacks should be enough to kill an enemy after expunge.
Here's where it really comes down to personal choice.
HP for Quints really help early game, but aren't as effective later.
Armor Pen is always good for marks however you can also choose crit % or crit dmg.
I haven't tested the differences myself but im currently using armor pen and im liking it.
I've also heard of some going pure atk speed and getting more damage focused items. (again have not tried this myself.
You'd want to farm as much as you can focus on last hitting preferably find a tank to lane with or one with a good stun (alistar, amumu, morgana etc) this allows you to place high poison stacks and most likely you'll get a couple kills if your teammate is any good. You can choose to mid lane if your opponent is not Ashe, Annie, Heimerdinger, Ezreal. However if there are better options (most likely like one of the 4 i stated earlier). I realize that twitch is easily gankable however just play safe w/ stealth + focus on last hitting again like i said don't cross the middle point and go back to kill forest creeps when your creeps hit opposition tower starting from level 8. Get lizard asap then go gank.
For my item build its flexible. the order of the Black Cleaver, LW, Zeal, are depending on the enemy team and how easy it is to kill them. If they are really tanking i generally go LW. If there is alot of team battles, AOE power (amumu) on my team then i go Black Cleaver. If im killing them fairly easily (not too tanky team) ill go Zeal then BC. As long as your start was not terrible you should be able to dominate. If the game lasts very long and you still have extra gold after completing the build switch out your Executioners for a Bloodthirster and switch the berserker boots for Boots of Mobility.
Other Notable items vs caster heavy teams would be Wits End + Mercury Threads.
PS. The crit rate is actually about 80% not 90% as shown on the stat since you upgrade phantom dancer last (6th item). You've really got to try this build before you say it sucks also. thanks