Dragon vs. Wizard

[Beleriphon]

I believe only the Brass dragon can take Permanent Emanation: AMF without class levels. Why? Because to take the feat you must already know the spell. All other dragons take their feat at 30 HD and also gain 6th lvl spells at the same time-so they can't pick PE: AMF because they don't meet the perequisites until AFTER they've taken AMF-and thus after CR 20.

Also, the Wizard could get Hide From Dragons and a Gate scroll. The dragon cannot detect him. The Wizard can summon a 40 HD outsider to tear the dragon apart.

I already pointed this out, but there is no stipulation on the max CR of the dragon in question. So my hypothetical CR46 level 20 druid Great Wyrm Red dragon pwns the 40HD outsider. And the wizard that summoned it as well.