There is no XP cap in the Black Pits but a level cap, which is 10 for everyone.
Which means a Fighter can reach the level 10 at 500.000 xp while a Mage will reach the level 10 at 250.000 xp.
A multi Fighter/Mage will get to the level 8/8 I think, because multiclass and dualclass character take the lowest XP cap of both their class, in that case 250.000.
Comments
There is no XP cap in the Black Pits but a level cap, which is 10 for everyone.
Which means a Fighter can reach the level 10 at 500.000 xp while a Mage will reach the level 10 at 250.000 xp.
A multi Fighter/Mage will get to the level 8/8 I think, because multiclass and dualclass character take the lowest XP cap of both their class, in that case 250.000.