Cumbrous Reflexes( Savage Species, p. 31)
You have a greater chance to resist attacks against your agility, but at a cost.
Lightning Reflexes (PH) ,
Before rolling a Reflex save, you can decide to activate this feat, which gives you a +6 bonus on your saving throw. After the saving throw is resolved, regardless of the result, you are prone and dazed. For details on these conditions, see the Condition Summary in Chapter 3 of the DUNGEON MASTER's Guide.