good points all,
scalable feats are usually a no-no . . . the only thing i can think that is even close is how a phb ranger can just automatically take imp. twf later on w/o ever having to take that feat.
i like the idea of a dwarven defender having to take dwarven toughness. possibly if the dmg came out after MotW it would be so.
3 hit points is a matter of life and death at all levels, even 1 hitpoint is, and we all know about that to some extent. while i don't allow dodge to be a +1 ac accross the board (i just have it vs. one peron / creature) i was thinking having to make the previous toughness feat a pre-req for the next is kinda crazy, and not worth it. (x number of hitpoints at the cost of 4 feats?)
the only possible way, i think, is to balance the mechanic i am altering. i'm adding something else which scales with power of class (or classes) level. your fort save increases already, and i'm adding something to that increase. it would only be fair, then, to make a feat which allowed dodge to scale accordingly (dodge, elven dodge, cats dodge, sprites dodge . . . who knows? what i do know is that dodge has to go from that name. maybe elven reflexes, cats reflexes and something else?)
while this is a cooler idea the more i think of, we'll have to introduce a scalable feat which adds a bonus to the will saves. (a headstrong type of feat? the problem is that while there are feats like lighting reflexes and iron will, along with feats like dodge and toughness, i don't think there is a requisite feat along the theme lines of a willpower mechanic. i can see high fortitude (from high class level), improved fortitude (i think that's the feat name for the +2 on fort saves) and toughness going hand in hand. i can see a high ref. save (from high class level), improved reflexes (+2 to reflex saves) and dodge being in the same family. but what about willpower?)
while many are against this type of feat, wouldn't it at least be fair to have a feat which grants something special for having a high base save?
high fort --> vanila save feat (+2) --> scaleing toughness
high ref --> vanila save feat (+2) --> scaleing dodge
high will --> vanilla save feat (+2) --> scaling mechanic.
fort gives you more hit points, ref gives you a higher AC, will would give what?
(as i continue to think this through, i'm glad ref doesn't give a scaling ability to the "imp init" feat . . . because then everyone would like to qualify for that)
what is a feat that is wisdom / willpower related (that isn't the iron will feat) which is viewed as a weak feat in the long run? (as toughness is, and as dodge is)