If there are two concealment conditions at play does the attacker have to make two flat checks? For instance, attacker is under the influence of Shroud of Night and all creatures are concealed to it. The player it is attacking has Blur or Mistform.
Two checks or just one? I'm guessing there is a rule somewhere about what happens when the same effect is in play more than once but it's not jumping out at me.
One. And there's always a rule! :)
Flat Checks
When the chance something will happen or fail to happen is based purely on chance, you’ll attempt a flat check. A flat check never includes any modifiers, bonuses, or penalties—you just roll a d20 and compare the result on the die to the DC. Only abilities that specifically apply to flat checks can change the checks’ DCs; most such effects affect only certain types of flat checks.
If more than one flat check would ever cause or prevent the same thing, just roll once and use the highest DC. In the rare circumstance that a flat check has a DC of 1 or lower, skip rolling; you automatically succeed. Conversely, if one ever has a DC of 21 or higher, you automatically fail.
Thanks. Trying to envision a scenario where a flat check would ever be a 1 or 21 now :-/