User blog comment:Shigfugjum/Another Vel'koz Blog/@comment-22338397-20140311144159

While I must say that this was an interesting read, you seem to be rather misinformed on how Magic Resistance works. Your opponent's effective MR (so after you count your own magic penetration) works by reducing magic damage by a PERCENTAGE. It doesn't matter if you deal one big chunk of damage or 5 small ones, the end result is the same. Your point on the base damage of his ult still stands though, which makes Haunting Guise an attractive option. It also gives a nice buffer of HP and can eventually be upgraded to Liandry's Torment like you said, giving Vel'Koz some additional poke/siege power with his Q slow, apart from being that "Mid-Range Combo Caster".

As far as Athene's Unholy Grail goes; even if know how to properly conserve mana, it's still one of the better CDR items that allow you to more often apply your spells' good base damages or their utilty (in Vel'Koz case just the knockback and slow, but they could prove critical for a no-escape squishy). Could also be replaced by Morellonomicon, if you really have to deal with extreme enemy healing.

Lastly, I would like you to consider Banshee's Veil. Not only does it give you that MR and health buffer, it protects you from those hard engages that Vel'Koz especially dislikes, from high impact poke (e.g. Nidalee Spears) and makes it a lot harder for the enemy team to simply send one CC your way when you channel your teamfight-changing ultimate. It might also help against assassin's burst where Zhonya's might be nonpractical because either the damage is instant/unpredictable or if it includes CC that prevents the active (e.g. LeBlanc silence).