Originally Posted by
squeekenator
10 + 12 (1/2 HD) + 5 (Con mod) +2 (Ability focus) = 29
And yes, the DC is very high, and it will kill people lots. But keep in mind that it's a CR18 monster who deals insignificant damage with its regular attack (also, everyone has a cloak of resistance +5 at that point). If it ever tries to take on a full party, it'll get wizard-blasted out of existance in the first round of combat, and by that point the party cleric can be preparing multiple Miracles, so you can wipe clean all the ability drain it deals without much difficulty.