Hellknight PrC on 10 or 15 level

[Waldham]

Hello,
In the Pathfinder AP - Council of Thieves, the Hellknight PrC build on 15 levels, but in Inner Sea World guide, on 10 levels.

So must a player take the progression on 10 levels ?

Or the player can progress then on 15 levels ?

Thanks for your future answer.

[Are]

Paizo decided they didn't want to have a 15-level PrC in the game, so they recreated the Hellknight PrC as a standard 10-level PrC in the Inner Sea World Guide.

A player who wants to be a Hellknight should ask his DM/GM which version he/she wants to use in the game.