The Perfect Hex Core has one of the highest single-value ability power bonus in the game, at 168 AP (Outclassed only by a Meja's Soulstealer with 19 stacks, or a Seraph's Embrace at 3600 or more mana). However, it is usually easier to build the Perfect Hex Core, than keep Meja's Soulstealer very-nearly-fully stacked.
It also combos well with Rabadon's Deathcap , and the two together provide 374 AP (Including Rabadon's passive). The Archmage Mastery will increase the total to 393 AP.
While unstated, Viktor does not gain the Glorious Evolution until after he has used each of his augmentation points.