If you're going to stomp your lane, pick up tear since you won't really need the immediate powerspike
If you're worried about a hyper aggressive enemy laner, start brutalizer though, but it means you can't spam Q much
Get the other item after you finish the first, then finish manamune and work towards either Frozen Heart, Black Cleaver or Ghostblade - FH is god tier if the enemy team has a lot of ADs
Black Cleaver is great if the enemy is split AD/AP, combined with your E it lets you shred about 50% of the enemy's armor and with your passive -15% damage dealt, you can tank pretty much anything in the game
Triforce is a good last item, every time you spam Q you get an extra bunch of damage, plus the slow proc on the phage portion lets you chase well
Boots3 is honestly one of the best things, you don't need CDR boots with the other items you have, mercs are good if you're up against a veigar or someone else with heavy CC, ninja tabis are a bit weak however
Runes heavily depend on matchup, 21/0/9 is the obvious choice for a bit more early CDR and lane pressure, but 9/21/0 or 0/21/9 means you won't die if you're against Fizz since he can just jump to avoid your E lock on. 9/0/21 is shit.
AD reds give you a really powerful level 3 spike, but arpen scales a bit better into mid and late game. You need mp5pl yellows, even with tear you run out of mana instantly in lane. Blues are usually flat MR. Quints are flexible, either flat/scaling health, movespeed, or AD/pen. Do not take gold generation runes, you are all about early game pressure.