Dodge bonus

A Dodge bonus is a bonus to AC. Note that dodge bonuses stack with each other, contrary to most other AC bonus types.

Source of dodge bonuses:
 * Feats
 * Combat expertise +5 (also gives a -5 penalty to attack rolls)
 * Defensive fighting +2 (also gives a -4 penalty to attack rolls)
 * Dodge feat +1
 * Mobility feat/item +4 (only while tumbling)
 * Uncanny dodge +4 (rogue and barbarian only)
 * Improved uncanny dodge +6 (rogue and barbarian only)
 * Inspire Heroics +4 (level 15 bard buff)
 * Enhancements:
 * Favoured Defense I to III +2-4 (Ranger only, vs. favoured enemies)


 * Fighter's Mobility I to II +1-2 (fighter only, only while tumbling; requires Mobility feat)
 * Giant Dodger I +4 vs. attacks from giant-type creatures (dwarf only)
 * Items:
 * Alchemical Armor Ritual +1
 * Alchemical Shield Ritual +1
 * Chaosgarde bracers +2 (lawful alignment only, from Xorian Cipher)
 * Chattering Ring +3 (The Titan Awakes raid loot)
 * Dragontouched Armor tier3 property +3
 * Icy Raiment outfit +4 (from Ghosts of Perdition, The Subterrane - Central)
 * Racial:
 * Dwarf +4 vs. attacks from giant-type creatures (dwarf only)
 * Spells:
 * Haste +1
 * Haste Guard proc effect +1

Other common bonuses to your armor class are armor bonus, shield bonus, deflection bonus, dexterity bonus, natural armor bonus, and miscellaneous bonus.

Dodge bonus cap ?
It is written in DDO user manual (p.74) and in PnP book (need citation), that dodge bonuses only stack up to a maximum of 10. But that is not really the case in game. You can benefit from more than 10 dodge bonus. It is unclear whether it is intensional or not.

Dodge bonus item stacking

 * "The dodge bonuses for multiple chattering rings are being treated as coming from the same source so they do not stack." - developer Grral
 * "Identical magnitude dodge bonuses from treasure do not stack in DDO. (With the exception of the Eldritch Ritual Shield/Armor improvements, when we renamed those to "Dodge". We'll rename those yet again to be clearer that those stack with everything but themselves.) This is an intentional deviation from the basic D&D rules." - developer Eladrin, forums.ddo.com