dragon is canonical because wotc said it was. they put the 100% official material stamp on just about every one by paizo. other opinions notwithstanding, whatever wotc says is official, is.
My god, rainbow avatars have a theme here.
A.
Hybrid Horrors
Few creatures or characters prove more dangerous than a necromancer who pairs with a powerful transmuter. Such a duo can combine animate dead and various bizarre breeding experiments to produce a corps of elite undead capable of tearing apart any living creature.
How?
It's simple, really.
The necromancer's level limits the number of zombies and skeletons he can control. Monsters usually don't gain more Hit Dire with the addition of a template, but this generally do gain ability score increases, often to Strength and Dexterity.
For example a 6th-level necromancer can control two ankheg zombies. Alternatively he can control two half-dragon ankheg zombies, two half-fiend ankheg zombies, or even two half-fiend half dragon ankheg zombies (remember, you ran slack multiple templates on the same creature). Of course. your DM might not always present such creatures for your party to slay, but that's why your necromancer has a transmuter ally with access to polymarph any object. The skeleton of a squirrel can become the dead body of a dragon turtle with the casting of a single spell.
Because I don't see
any text saying PAO can be used to add templates to creatures, it suggests templated undead are pretty powerful but if the DM isn't throwing them at you it suggests that you turn one object (a corpse) into another un-templated-
object (a corpse) using PAO.
B. The books and
movie are "D&D" per WotC. Am I to expect some shitty remark that Wizards can cast Somatic spells even if oh idk, grappled by a wall, because screw the
rule books? Dragon is 2nd party and I'm certainly not canonizing Warhammer is D&D material because Dragon liked to advertise and reference it. My line is drawn on 1st party resources and yours is clearly at "what-ever-some-one-says-on-some-forums".
C. Errata states any contradictions presented in rules (that's
rules btw,
suggestions don't count), such as no templated creatures, is prioritized by updated sources first. Which is a chain of like the FAQ, Errata, PAO and all of it's various updates from the RC, PHBII, DMGII?, CM?, the original printing, WotC's online articles, and so on. Long before we ever hit something at Dragon's level. And clear back at PAO it's self we've got rules that say no. So honestly, even if it did say yes and it don't, who the hell cares?
I wish I nipped this one in the bud when ever it was first posted, clearly people are running down hill with it as "fact".