Master of Shrouds by RAI?(is it worth it?)

[Maho-Tsukai]

I am going to be applying for an epic gestalt game soon and my gestalt will be a Necropolitian Dread Necromancer 19/Pale Master 2///Cloistered Cleric 21 using dynamic priest to make the built totally cha focused and use the cleric side for animation, utility, buffs and other things that don't require saves(Dynamic priest changes the cleric casting stat to charisma for everything except DCs) while offensive casting is left to the DN side.

However, I would like a PrC for the cloistered cleric side that is themeaticly related to necromancy and advances rebuking. Looking through vairous pdfs and books I found the master of shroudes but most people say the class is not worth it without an early entry method. The game is rather strict about optimization and things ranging from DMM presist, a number of templates, vairous PrCs such as incantatrix ect.. are banned.

So I figured since the game is medium-low OP that taking Master of Shrouds without any cheesy early entry may not be all that bad an idea. It advances rebuking, gives me some nice summons and fits the "necromancer" type of character I am making. True, it costs me one CL but in the OP level of the game that lost CL is not really an issue since I will already be one of the most powerful characters in the party anyway being one of the only two fullcaster/fullcaster gestalts so I can more then afford to lose a few CLs.(The other is a wizard/euradite and everybody else is a gish of some kind or a mundane and/or manuver using melee fighter.)

[Yuki Akuma]

Does it allow you to cast 9th-level spells by 21st level?

If yes, it's worth it.