Starting with two points into shadow lock and one into siphon leads to an explosive entrance into any game. With the right teammate to swoop in or a player caught off guard you can secure the first kill in most matches. Running the spear of the magus first also ensures you provide targets throughout the match and allows you take over the lane with your CC and the passive boost to damage you can apply to any who push too far in. Afterwards build based on the need for the particular game. The other items are the ones I use most commonly. I stopped building stacks on Nox a long time ago and my game has improved dramatically as I can build for support or simply power/penetration. This build also works well with another mage on the field.
Spear of the Magus
PASSIVE - Whenever you damage an enemy god with an ability you mark them to take 7.5% increased damage from all sources. This effect lasts for 7s and can only occur once every 15s.
PASSIVE - Enemies hit by your abilities have 40% reduced healing for 5 seconds.
Rod of Tahuti
PASSIVE - Basic Attacks and Abilities gain 25% additional Magical Power against targets below 50% Health.
Calamitous Rod of Tahuti
PASSIVE - Basic Attacks and Abilities gain 25% additional Magical Power against targets below 50% Health. <n>GLYPH - Successfully hitting an enemy god with an ability calls down a meteor that lands after 1s, dealing 100 (+35% of your Magical Power) damage in a 15 unit radius. This effect can only occur once every 30s.
Spear of Desolation
PASSIVE - If you receive a kill or assist on an Enemy God all of your non-ultimate cooldowns are reduced by 2 seconds and your ultimate cooldown is reduced by 6 seconds.
PASSIVE - Whenever you damage an enemy god with an ability you steal 8% maximum mana as well as 6% maximum health from the target. The Stats remain stolen for 45s and targets affected can have multiple Buffs and Debuffs at once. This can only occur once every 15 seconds.
PASSIVE - You gain additional Magical Power and Lifesteal scaled from missing Health. This caps at 100 power and 20% Lifesteal at 25% Health.
PASSIVE - Damaging any enemy with an ability restores 4 health and 6 mana. Can only trigger once per target per ability. Can be upgraded at level 20.
PASSIVE - On successful hit of an Ability you gain 1 stack. At 3 Stacks your next Ability that damages an enemy God will deal bonus damage equal to 25% of your Magical power to each God hit, and will heal yourself and allies within 20 units for 30% of your Magical Power and will consume the 3 stacks.
PASSIVE - Your Healing obtained from Magical Lifesteal is increased by 25%. Your Magical power is increased by twice the amount of Magical Lifesteal you have.
PASSIVE - Using an ability gives your next Basic Attack within the next 8 seconds +75% of your Magical Power as additional Magical Damage. The effect can only apply once every 2 seconds.
PASSIVE - Every 10s the Pendant activates, subtracting 1s from all of your abilities currently on Cooldown. The initial countdown will not start until you leave the fountain.
PASSIVE - Your abilities deal an additional 2% of the target's maximum Health as Magical Damage. If the target has over 2000 Health, your ability bonus damage scales up. This effect reaches a maximum of 9% Maximum Health damage at 2750 Health. Subsequent hits on the same target do half the bonus damage for the next 3s.