I'm A Banana
Potassium-Rich
Point #1: Know your party. If your cleric can turn as a 21st level cleric, and you want to put in an undead BBEG, you want to put in an undead BBEG that cannot be turned by a 21st level cleric. Pump up the Turn Resistance, the HD, fill the dungeon with lesser undead, etc. Your cleric is hellishly good at turning -- make sure that he *can't* end the adventure on that anticlimax.He was three levels higher than the party with +4 turn resistance. The 15th level cleric turns as a 21st level cleric. Rolling on the table she received a Cleric level +1 on the turn check, not a very hard check, and turned a BBEG 7 levels higher than her level. 7 levels higher. That is obscene.
Point #2: Don't be surprised at power problems if you're tinkering with the rules. There's a reason you can't wear a periapt and a phylactery at the same time -- they have a lot of the same powers, and uniting them would make things quite mighty. Admittedly, this is hardly revolutionizing the game, but it is something to watch out for.The cleric I mentioned added the Phylactery of Undead Turning to her Periapt of Wisdom. At high levels, such enhancements to already existing items are affordable to a group of 16th level characters who just finished looting a sixteenth plus level adventure and selling the booty.
Point #3: Think about the effects. Turned undead run. If you don't want the BBEG to run, think about other effects turning can have -- CD has advice for just such an occasion (turning does damage). You can mix up the effects in general, or just for a specific monster; giving a Vamp a special quality or a feat where instead of running they take damage.read the PHB, under Effect and Duration of Turning it says- Tunred undead flee from you by the best and fastest means available to them.
There's no reason that a DM who knows about his party should be caught by surprise by a relatively common roll, IMHO.
Now, there are issues with Turn Undead, and I'm all for changing it (the CD's damage variant is my favorite so far), but it's not a problem with 3.5 or anything; each campaign needs to decide what's right for it, and what it can do.