Came out of the stairs on level 3 and got ambushed. A metric crapton of Hill Giants, Dark Wizards, Trolls, Clerics, Assassins, Ettins, and warriors. After the head bad guy monologued, my party leader said "We're doomed", and for once I believed her.
First thing I noticed was that the Dark Wizards had 77 hp. "Wow", I said to myself, "that's a lot of hit points for a wizard. Wonder how that happened?" I checked their stats. No Toughness feats. 9th level Wizards. 17 Con. They should have 51 hit points on average. Even if they had MAX, they should only have 63 HP. So, boo, hiss, foul.
While I'm at it, let's calculate the EL of the encounter and see just how ridiculous they have stacked the odds against us.
First off, a 9th level wizard should be a CR 9 enemy, yet they are listed as a CR 8. So that's wrong. Let's see if any of the others are off:
Level 8 warrior is listed as CR 6: wrong. Should be CR 7. On page 38 of the 3.5 DMG, their CR is equal to their NPC levels -1.
General Grighor listed as CR 11: wrong. He's a 12th level half-giant Death Knight. He should be CR 12.
Pizarra listed as CR 9: again, wrong, she's a level 10 Warlock. Should be CR 10. Starting to notice a trend here.
Evil Drake Cleric: Level 9, listed as CR 8.
Hill Giant: listed as CR 7, which is correct, but it is advanced thusly: Higher stats, a couple bonus feats, higher saves and HP (probably from raised stats). I would probably put him closer to CR 8 due to the modifications.
Ettin: now here it gets kinda weird. The one in the MM is a CR 6 and the one in KOTC is 7. However, the one in the game is remarkably similar to the book except for the feats. Pounce?!? Improved Grapple and charge? Superior Two-Weapon Fighting? He doesn't even have a high enough dexterity to qualify for that one. You've basically got a glass juggernaut here. He will charge up to you with his reach and pounce upon you with all his attacks. If your AC isn't up to snuff, you will be snuffed. Very likely, he will just run up to you and grapple your spellcaster so his buddies can smack him to death.
Troll Death Knight: ouch! From the looks of the stat block, he has two levels of Death Knight. CR 7 is actually appropriate for this one, although once again he gets Pounce, which is way overpowered for an ability which is why it is relatively difficult to get in P&P.
Cultist Assassin: Level 8 Rogue, should be CR 8, is listed as CR 7.
Now to figure out the EL of the encounter. Keep in mind that I have done virtually all the sidequests up to this point. I am level 8. A tough boss battle should be between EL 10-12. Anything higher and we're guaranteed a player death, higher than 6 above the party's level and it's probably going to be a party wipe.
6 Evil Cultist Warriors
General Grighor
Pizarra
8 Dark Wizards
3 Evil Drake Clerics
2 Hill Giants
1 Ettin
3 Trolls
4 Cultist Assassins
We'll calculate what the EL should be using his current numbers, then figure it based on what the CR numbers should actually be.
Using the calculator found at http://www.d20srd.org/extras/d20encountercalculator/ (because I am lazy), I am somewhat hampered by the sheer number of enemy types. It only has fields for up to 6 different enemies. Entering everything except for the Ettin, Trolls and Assassins, the calculator says that the EL is 17. Using D&D Math (tm), I can plug that EL 17 into the first field and calculate the rest as if it was one creature. That gives me a grand total of an EL 18 using the CRs listed above (which are nearly all artificially deflated by 1).
If I use the CRs as they really ought to be reflected, it comes to the same EL of 18. Guess we pegged the meter. Still a guaranteed party wipe.