Hecarim is a tanky/jungling/Dps character but i usually play him by damage which causes alot of physical damage on the enemy champion.You increase Rampage first so it will be easier to farm and lvl up at early games,make sure to bring Ghost for your Devastating charge which gives it more damage for all the movement speed it has.this build is not for tanking but if you were to team fight use rampage to hit all of them while it does that use spirit of dread and if you need to. you can use your ulti. Devastating charge can be use while saving your team mate, you activate it while running and while your teammate is running away from an enemy Charge at the enemy which knocks the enemy back and save your teammate's life.Do not use Devastating charge recklessly or you will might aswell die.Use your passive as a advantage on the enemys,Hecarim might get ksed alot but when they are low use devastating charge and rampage at exactly the same time (only if your really close to eachother) it will result to damaging the enemy faster at the same time.Hecarim ulti can be use for killing or for fleeing,
his ulti can go through walls but beware if there is any enemys on the other side.If there is another hecarim in the enemys team you can counter attack his devastating charge by using your devastating charge and once your about to collide you quickly use your rampage as a result for hurting the enemy's hecarim and yet he dealt no damage to you.You can use Devastating charge on the enemy's turret which deals more damage to the turret and you can use ghost to deal more damage,This can be used if the turret is low and your enemy is tower hugging with less health.
So thats my intro for all you beginner hecarim's out there make sure to vote :)