BSF
Explorer
Nerf the physical attacks of the Pit Fiend with a Protection from Evil spell. Even evil folk have reasons to have this available.
Blasphemy/Holy Word are wonderful solutions. Dismissal & Banishment may work as well. Even if you decide that they just send the PC to somewhere on the Prime, there is nothing saying it has to be right where the PCs are currently.
But really, you can point out the disadvantages all day long. In the end, Shapechage is still an impressive spell. It ought to be for 18th level. Don't focus on nerfing it too much, focus on making it relevant for both the advantages & the disadvantages. It is very challenging to use a straight module for a group at that level. The number of options that PCs of near epic levels have available is astounding. You need to tailor these challenges for each group.
Blasphemy/Holy Word are wonderful solutions. Dismissal & Banishment may work as well. Even if you decide that they just send the PC to somewhere on the Prime, there is nothing saying it has to be right where the PCs are currently.
But really, you can point out the disadvantages all day long. In the end, Shapechage is still an impressive spell. It ought to be for 18th level. Don't focus on nerfing it too much, focus on making it relevant for both the advantages & the disadvantages. It is very challenging to use a straight module for a group at that level. The number of options that PCs of near epic levels have available is astounding. You need to tailor these challenges for each group.