Improved Uncanny Dodge

[cbaidchris]

If you take levels into a class and pick up improved uncanny dodge and then you take a prestige class that also gives you uncanny dodge or improved uncanny dodge is there a way to replace these such as a specified variant or is it a thing where you should just pick your own class ability to replace it?

[Kuulvheysoon]

There are certain ACFs that let you trade out (Improved) Uncanny Dodge for Base/Standard classes. There is no way to do this with prestige classes, unfortunately. You'll be stuck with a useless class features (although those classes that grant it usually stack with the others that do).

[SolioFebalas]

As mentioned above, there are only ACF that can trade your uncanny dodge.

I know such ACF only for two classes Barbarian:

1) Bonus Feat (SSt, p 44): Gain a bonus feat, lose improved uncanny dodge.
2) Fangshields Barbarian Substitution Levels (CV, p 40) 5th level: Awesome Charge (make a charge attack as though with Awesome Blow), replaces uncanny dodge.
3) Goliath Barbarian Substitution Levels (RS, p 150): add knowledge: nature to class list; 5th level: Fortification (25% chance to prevent crits and such), lose uncanny dodge.
4) Half-Orc Barbarian Substitution Levels (RD, p 159):
2nd level: Reckless Charge (+4 attack while charging, -4 AC), no uncanny dodge; 5th level: Insightful Rage (+4 will vs. illusions), no improved uncanny dodge
5) Uncanny Bravery (DrM, p 14): Gain immunity to draconic presence and resistance to fear instead of improved uncanny dodge.

and Rogue:

1) Changeling Rogue (RE, p 121): Add one knowledge skill to class list, 10 skills per level, 8th level: Mutable Anatomy (50% chance to negate extra damage from a critical or sneak attack), lose uncanny dodge.
2) Disruptive Attack (PHB 2, p 57): Don't gain uncanny dodge. Whenever you attack a flanked or flat-footed target, you can sacrifice your sneak attack to give them a -5 to AC.
3) Goliath Rogue Substitution Levels (RS, p 152): d8 hitdice, add survival to class skills; 8th level: Fortification (25% chance to prevent crits and such), lose uncanny dodge.
4) Uncanny Bravery (DrM, p 14): Gain immunity to draconic presence and resistance to fear instead of uncanny dodge.

[Curmudgeon]

If you're playing a Barbarian or Rogue and have already picked up Uncanny Dodge/Improved Uncanny Dodge from that class, ask your DM if you can use the retraining rules (Player's Handbook II) to swap it out for one of the alternatives SolioFebalas mentioned.