This build is all about speed. Hot, nasty, badass speed. -Eleanor Roosevelt 1945

This build takes full advantage of the movement speed->atk damage. Naturally we put enough into Utility to get the 2% movement speed boost. 8 points in Defense to keep your health up and unsquish you up a bit. 14 in attack, cause well, that's what we're doing.

Ghost- With the point in summoner's wrath ghost gives you a 35% movement speed increase. A) you blaze across the field to chase people down in seconds or escape with barely a scratch. Don't forget you also get attack damage for it because of Hecarim's passive, making it extra awesome for chase downs.

Ignite-I use ignite mainly for early game with enemies get behind their turret. You can really put anything you want here.

Boots first, no question.
Sheen gives you your first turret demo tools. Once you get sheen (and trinity force later) position yourself in between the turret and the enemy wave of creeps. While attacking the turret use Rampage. Your attacks will deal bonus damage to the turret and your creeps will be free to tank it for you.
That's pretty much it. From then on it's all about movement speed and attack speed.

Turret combat we went over.

Warwick move aside. Hecarim is the new gankmaster. Open with charge and maneuver so that you hit them on the side they will be running away to, knocking them back away. Use spirit of dread mid-charge and use rampage on landing. If necessary use Onslaught of Shadows to move past them and fear them back the opposite direction for more maneuverability. The important thing is to not autoattack much while chasing. Run next to them and spam Rampage. Autoattacking will slow you down while rampage doesn't, plus it does more damage. In no time they're dead and you're off the your next victim.