Soul Eater

Soul Eater This is your Core ability to stay in lane to the most Harrass based Champions. If you farm under Tower with 6% Lifesteal Quints and Second Wind you can't get poked out of the lane easily. This keeps you alive!

Siphoning Strike This Baby here is, what Nasus makes Nasus. Stacks on this Badboy are your only Damage output. Farm > Kills for Nasus. or well at least in early. Tell your jungler not to gank until you get some Q stacks because you don't deal Damage in the early Game! Max this ability first and try to get every Creep lasthittet with this. If it is too risky to reach a creep take it with Spirit Fire. but dont do this too often or you will get oom too fast.

Wither In 1v1's this is your "Ace in the Hole". He thinks he can trade? Nah here take this Auto Attack Slow! But it's not only AA slow its movement speed slow aswell. Use it to slow the ADC's in Team fights or to reach retreating enemys.

Spirit Fire This Ability is the Ground you want to fight on. The decreeased Armor helps you and your team to deal more Damage on all enemys standing in it. but dont use it too often for farming creeps or pushing the lane. The damage on early levels is not that useful for that + u want Q farm and not pushing so freeze the lane.

Fury of the Sands Your Avatar Ulti. More HP, More Damage, More AOE, More Everything! It makes you a Horror to fight in 1v1 and even in 2v1. It makes you nearly not towerdivable during laning. If your enemy laner is trying to fight/all in you, use it when u reach like 1/3 or half HP. If your enemy is using his ult too fast (like Renekton) just retreat and use yours when his ult is over.