based on the old "godyr" build.
Ver : 1.2
Updated : 04/01/15

Soul Eater (Passive) :
Nasus drains his foe's spiritual energy, giving him a natural 10 / 15 / 20% life-steal.
Great great passive for jungle, also working with Siphoning Strike

Siphoning Strike :
Nasus's next attack will deal an additional 30 / 50 / 70 / 90 / 110 damage plus the extra permanently gained damage. Siphoning Strike permanently gains 3 damage whenever it kills a unit. This bonus is doubled for larger creatures, such as enemy champions, cannon minions, the large wolf, and Baron Nashor.

Always be mindful to last hit the lager monsters in the jungle with this skill.
The triggering attack will apply other on-hit effects, Iceborn Gauntlet and Feral Flare bonus will trigger.

Wither :
Nasus ages his target, slowing their movement speed by 35% with an additional slowing effect increasing over the duration of the spell. The target's attack speed is also slowed by half the amount, initially slowed by 17.5% and increasing over the duration. If the duration of Wither is reduced, the added slowing effect is applied faster.

Our main and the only CC, There is a high mana cost to this so use it with caution in early game.

Spirit Fire :
Nasus unleashes a spirit flame at a target 400-radius area, dealing magic damage to enemies caught within. The spirit flame burns for 5 seconds afterwards, dealing magic damage each second and reducing the armor of enemies within the area.
Armor Reduction: 20 / 25 / 30 / 35 / 40

this skill help ous SMASH ! the head of our enemies.
always cast Spirit Fire on the target and than SMASH him with Siphoning Strike

Fury of the Sands
Nasus summons a sandstorm to empower himself for 15 seconds, enlarging his size, gaining bonus health and increasing his attack range by 50 (175 total range), also count for Siphoning Strike.
While the storm rages, enemies within 175 range take magic damage equal to a percentage of their maximum health (max of 240 magic damage per second per enemy).

Few Masteries that i want to explain the reason that i took them.

Oppression 1/1
Reduces damage taken by 3% from enemies that have impaired movement (slows, snares, taunts, stuns, etc.)
Every enemy with Wither on them will count under that skill.
very Useful when Fighting 1vs1.

Legendary Guardian 4/4
+4 Armor and 2 Magic Resist for each nearby enemy champion.

i know that alot of player preffer Second Wind.
but 20 armor and 10 magic resist in full team fight is better than +10% lifesteal (2 more points with the current build).
also dont forgot that all the early game we are going to play without def items.
you can change it if you want but i dont recommend it.

Summoner's Insight
Reduces the cooldown of Summoner Spells by 10%

good for quick Smite and Reduces the Teleport CD to 270 or 216 if Teleporting to an allied turret.

at the start of every game we want to farm the jungle first time this way :
1.Lizard Elder: Red Buff
2.Wraiths
3.Wolves
4.Ghast
Recall and buy Madred's Razors
than Teleport to top lane.
5.Ancient Golem: Blue Buff