Epic feat: self concealment cumulate with other "miss chance" abilities or spells?

Question

One of my players uses in combat the spell displacement (PH 223) allowing the 50% miss chance of attacks.

He also has the epic feat "self concealment" (10%). This feat is on the -epic level handbook pag 66- which is d&d 3.0. (as far as I am aware there is no manual for epic levels in d&d3.5).

We know that the effect of the feat does not stack with the effect of the spell (60% is not allowed). But the player is asking me (the dungeon master) to roll first if I pass his displacement (50% miss) and then roll again if I pass his self concealment (10% miss).

The player also has the prestige class of perfect Wight (epic handbook page 34). When the player becomes incorporeal it allows for a miss chance of 50%.

Does this mean that to hit him I need to roll the dice to pass 3 miss chance (50% 50% and 10%)?

Is this right?

Answer 1

None of them stack, and rolling multiple is stacking them; use the highest miss-chance.

Player's Handbook, 152:

Multiple concealment conditions (such as a defender in a fog [DMG 94] and under the effect of a blur [PH 206] spell) do not stack.

If the concealment and the incorporeality miss chances were both rolled, the chance of a successful hit would be 25% (50% × 50%). If the Self Concealment were rolled after that, that would reduce the chance of a hit by a further 10% of the 25%, so 22.5% chance of a successful hit.

So, the fact that the chances do not stack also implicitly means that the miss chance is rolled only once, otherwise the percentages would effectively stack, which they explicitly do not.

The general rule is that unless specified otherwise, only unnamed numerical bonuses and instantaneous effects stack or otherwise combine to greater effect [PH 171]. So, the best miss chance any creature is likely to find is 50% for total concealment, and you don't roll more than once unless an ability explicitly tells you to, such as the blind-fight feat [PH 89]

...every time you miss because of concealment, you can reroll your miss chance percentile roll one time to see if you actually hit.

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For what it's worth, the Rules Compendium, which is not regarded as a primary source by some, also states that multiple miss chances don't stack [32]:

If a creature receives miss chances from multiple sources, such as from being incorporeal and having concealment, only the highest miss chance applies.