Well, to be fair, Mind Flayers shouldn't be listed as CR 8, either. They can fairly easily kill 8th or 9th level parties. Dragons also have the Awesome effect.<br/><br/>Regenerators do indeed have problems as PCs - as puzzle monsters (the puzzle being "What does it take to kill this?"), the PCs need to find the special solution when they fight it (and they only fight it once or twice), but as a PC, it means everything the DM uses will actually need a way around it in order to provide a challenge. One possible solution is to say "If they spend a full round action (minute, whatever) cutting your head off when you're down due to nonlethal, then you die." But that's a houserule. It means they're tough, but in a TPK scenario, they can still suffer a coup de grace and be slain.<br/><br/>If you do that, then there isn't much that's special, and they're just brutes with a little extra resilience.<br/><br/>Monsters that make minions and control things? I'd care, except that PCs can already do that with spells and all that. So if it's a problem, then it's already a problem that exists without the monster, so needs to be fixed across the board. If it's *not* a problem, then, well, it's not a problem.<br/><br/>And apparently ability scores should also be tinkered with, because when the numbers get too big, it can really have strange results. Specifically, if it has a score above 15, then assume it was made with the Elite Array, so subtract 15 from the highest score, then 14 from the next, 13, 12, 10 and finally 8 from the worst score. That gives you somewhat reduced ability mods. If the stats are fairly ordinary, then leave them alone, or if they're a low, flat bonus across the board (+1 to everything, for instance) then assume they were made with three 12s and three 13s.<br/><br/>Again, it's all a bit of a "patch it together", but you do what you can.