Fury 5 - Well I hope I don't have to explain why this and not Sorcery. Attack speed is better for ADC. Period.
Fresh Blood (new) - This mastery boost your 1st Auto-Attack a little bit. Since I like to play agressive during phase and poke my enemy from time to time I believe that this might be a good mastery for Draven players. It is also interesting that it scales with level: Higher level means more bonus damage.
Vampirism - A little bit sustain on the lane won't hurt.
Bounty Hunter - This is a mastery that i favor the most. The highest possible increased damage if you manage to get 5 "unique" kills. In total you will get 7,5% increased damage. You won't probably get that 7,5% in each game, but it's still better then 5% you could get from Double Edged Sword (since you take 2,5% additional damage) or Battle Trance.
Battering Blows - Well I hope I don't have to explain why this and not Piercing Thoughts. You're Draven, you deal PURE AD damage which means you need armor pen. Period.
Warlord's Bloodlust - I have made some final conclusions. And I believe WB is the best keystone for Draven. Your AA usually do enough damage to kill people. Not to mention - lifesteal is just priceless on this patch.
Savagery - Before 5.22 Savagery used to give you 2 points. Now it's 5. It's pretty good to have it. It helps you last hit minions A LOT. I'm not really sure about 'Wanderer' i mean movement speed is good, but it only procs when you're out of combat. I guess if you're good at last-hitting and don't have problems with it you can replace Savagery with Wanderer (but why would u since you gonna hit minions entire game)
Secret Stash - Ever seen a biscuit on ADC? No? Me too, but guess what? It's pretty awesome.
Merciiless - 5% damage to champions below 40%? Thank you i will take it.
Dangerous Game - We all know Dangerous game. Now it's 5% of mana and HP. It's good to have it.