Concealment

Concealment in DDO refers to Concealment Miss Chance

Concealment Miss Chance gives the subject of a successful attack a % chance that the attacker missed because of the concealment. If the attacker hits, the defender must make a miss chance percentile roll to avoid being struck. Multiple concealment bonuses of the same type do not stack, and currently every single one is considered the same bonus type - enhancement.

Enhancement bonuses to personal concealment are provided by:
Note: All of these sources are can be negated with the True Seeing (spell)
 * Item effect: Dusk. 10% enhancement bonus to concealment.
 * Item effect: Ghostly. Listed as a 10% bonus to concealment, but the effect blocks Blur spell and is confirmed to actually provide 20% enhancement bonus to concealment.
 * Item effect: Smoke Screen. 20% enhancement bonus to concealment.
 * Item effect: Blurry. 20% enhancement bonus to concealment.
 * Monk finishing move: Dance of Clouds: 20% enhancement bonus to concealment. Works on friendly NPCs.
 * Spell: Blur. 20% enhancement bonus to concealment.
 * Spell: Shadow Walk. 50% enhancement bonus to concealment (lost if you interact/fight).
 * Spell: Displacement. 50% enhancement bonus to concealment.

Enhancement bonuses to everyones concealment in a localized area are provided by:
Unlike the other above sources, none of these are negated by the True Seeing (spell).
 * Level 1 Spell: Obscuring Mist. 20% AOE concealment.
 * Level 2 Spell: Fog Cloud. 20% AOE concealment.
 * Level 3 Spell: Stinking Cloud. 20% AOE concealment.
 * Level 5 Spell: Cloudkill. 20% AOE concealment.
 * Level 6 Spell: Acid Fog. 20% AOE concealment (Blocked by Freedom of Movement and Red/Purple named are immune).
 * Level 8 Spell: Incendiary Cloud. 20% AOE concealment.

Note: Miss chance due to being Incorporeal are separate rolls from these sources, and thus stack.