I run draven with 1 Rune Page basically.
Only the last option of the Presicion tree I swap when facing a lot of bruisers and tanks.

conqueror as key rune.
It gives you Extra AD and Extra healing. I take this over PTS so i dont have to stack it up per champion in fights later on. while conqueror stays on max damage and healing once you have reached it in a fight.

Overheal as 2nd, when i play Draven i always get a Bloodthirster as first item. Both item and Rune give you a shield for excessive Lifesteal which stacks on top of each other. Which means you have a permanent huge shield when you completed this item.

Legend: Alacrity some extra attackspeed is great since you dont get to build it until 4th item in the build. you will have enough to since you have Bloodrush and Berserkers.
You will not need Bloodline because you will have 32% lifesteal in your Core build.

Cut Down Take this one when you face enemies who have more HP then you. 3 or more enemies is worth picking it.

Or

Coup de Grace is the Regular rune you want. It gives always good value.

2nd Rune page Sorcery

I always take these 2 cause i want that raw Damage on Draven.

Absolute focus this extra AD is most of the time on since you have insane lifesteal and are most of the time Full HP.

Gathering Storm scaling AD. Great for draven since you dont miss any early damage with this champ but get more damage over the time the game continues.

Berserkers you pretty much always take. You can swap them for Merc's when you face Heavy Magic damage or Tabi's when you face Heavy AD damage.

Bloodthirster Your First item.
This item really sets you off and you are able to trade constantly and be very aggresive. Like i said before you need to take Overheal to make the effect of the shield even stronger.

Immortal Shieldbow 2nd item.
Basically an improvement of the stats you already have. you got 115 AD, 32% lifesteal,68% attackspeed and 40% crit chance from these items. It also provides a shield when you get low on HP. Other legendary items gain 5 AD and 50 HP. So that's a nice 200 HP and 20 AD late game.

Infinity Edge your MUST as a 3th item. You get the extra Damage buff for crits now at 60% crit chance.
When you completed this you hit like a truck.

Rapid Firecannon a Good 4th item.
this item brings up your crit, range, movementspeed, attackspeed and it is super cheap only 2500

Last item is very situational i would say.

The collecter vs squisy champions.

Mortal Reminder vs Healers.
You can get the Executioner's Calling earlier if you need it

Lord Dominik's Regards vs tanks or bruisers.

Stormrazor is a legit option here as well. You already have a rapidfire cannon rapidfire cannon and the 2 improve eachother. It makes it easier for you to kite and it's easier to catch an enemy out as well since the slow is pretty strong it applies.