My Personal Build
My Build #2
Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
What Still Needs to be Done
Finish Summoner Spells Chapter
Laning Tips Chapter
Pros / Cons
Defensive Runes are almost always better no matter what, but on Vel'Koz they are especially good due to the fact that he has bad AP scaling. Its the same reason you don't want to get a Rabadon's Deathcap as an item.
Greater Glyph of Magic Resist
Greater Mark of Magic Penetration
Greater Seal of Armor
Greater Quintessence of Ability Power
You want to go down the Utility tree for the
as it is much better damage and utility wise, plus utility and penetration are much more important on Vel'Koz than damage, which is the base of the offensive tree. You might not get the penetration from
but you still get some from
Summoner Spell #1
Ignite is not a spell I recommend on Vel'Koz. Generally, you should never be in range to Ignite the enemy at all. Then it takes up a slot for summoner spell and you are left without anything defensive. Overall, Ignite is very risky to take.
Cleanse is my preferred summoner spell. I acts as a disengage by removing disables and gives you CC reduction, allowing/helping you escape, where Vel'Koz has none. It can also be used as a pursuit, though as Vel'Koz you wont need to be doing much of that due to your long range. This summoner spell is good on Vel'Koz for much of the same reasons as it is on Xerath.
Heal would be my second choice for your summoner spell #2.