Pretty poor build in my opinion. I feel as though archangel's staff and rod of ages are squandered investments on Veigar. Also, the magic penetration provided by sorcerers shoes is a much more useful passive than what you get from the CDR boots.

Some of your comments bothered me. For example, you said "[baleful strike is] NOT recommended to be spammed before level 6 as it can burn off your mana very quickly". This is quite opposite from what you want. During the early game, you should be using your baleful strike every time it's off cooldown for last hitting.

Indeed, Veigar is poor at laning early game and could potentially be zoned, but baleful strike actually becomes a very threatening nuke at level 3 because of its short cooldown and high damage. Between levels 1-6 baleful should only be used on the opponent for defensive purposes (i.e., as an intercepting blow whenever they try to harass). Once you hit level 7 it should be level 4 and it is now one of the highest damage single-target spammable nukes, and should be used offensively whenever possible.

Deathfire grasp should be included in every Veigar build. Quite frankly, if it isn't in your build you aren't doing it right.

I don't understand the logic behind your "impractical" guide (other than the name of it). I've accumulated over 1200 AP in some games by using standard Veigar items (e.g. deathfire, rabadon's, soul stealer, hourglass, abyssal, elixir); at high AP levels magic penetration becomes much more important than slight fluctuations in AP. To be honest, if you were to sell all your items and replace them with archangel staffs you just increased your chances of losing.

Finally, your skill order is kind of messed up (e.g. you have 3 levels in baleful at level 4 which is not possible).