This is the particular feat that Claudius is emphasizing:
Automatic: Still Spell - NWN2Wiki, the Neverwinter Nights 2 wiki
Still spell - is an otherwise useless feat.. EXCEPT for access to Automatic Still Spell. Then it can be an incredibly useful feat.
Sure, Auto Still (1-3) can allow you to cast spells at their normal level with out an armor check penalty for spell failure - thats good but not great.
What *IS* great is having Automatic Still Spell 3 voiding the spell failure rate when this spell is active:
Neverwinter Nights 2 @ GameBanshee
The combination is AWESOME.
(..without Automatic Still Spell 3 the spell is kind'a useless.)
With regard to classes and feats..
Regardless of class you get epic feats at 21, 23, 25, 27, 29.
With these feats you essentially have full access to all epic feats that your character has earned the right to have access to. This means that if you have still spell then at 21 you could spend your epic feat on Automatic Still Spell 1 regardless of what class you had for that level.
However if you also had a class specific feat (like a fighter's bonus feat at every other level), then you only get to choose what is available from the Fighter's feat selection. In this case Claudius is getting you Automatic Still Spell 3 as fast as you can possible get it by using the Divine Champions additional class-specific feat that DOES have access to Automatic Still spell at epic levels - and using it for Automatic Still Spell 2 (in addition to Auto Still 1) at level 21.
Again, Claudius's build is about as good as you'll get for what you've asked for.
BTW, be sure to pick up Empowered Spell from the meta-magic feat at character level 12.