Ogre Cave, Ogre Chieftain - Spell DC - Save Weirdness

[Sun Wukong]

Right, my character had base fortitude save of 20, with +4 against spells for having 20+ ranks in the Spellcraft skill. Therefore, I really do not see how my fortitude save roll was just 17. I could understand not getting the +4 from Spellcraft if the Destruction spell was a' spell-like ability' instead of a proper spell on the Chieftain, but what explains the -3? Does the Ogre Chieftain have levels in both Blackguard and Warpriest? What about the Goristo, is he the culprit here?

In my experience the save for that spell has just been 22, as spell like ability.

[Valefort]

It's a normal spell, 10 + 8 (wis mod) + 7 (spell level) = 25, I couldn't see anything particular with the Goristro and the Ogre has no aura either, however he has energy drain. Weren't you hit by that spell before ?

[Sun Wukong]

Well, if he somehow managed to throw Energy Drain and that took away 7-8 levels, then yeah, the fortitude save makes sense. But even then it should have left me with enough spellcraft to have +3 against spells. But then again, I do not think that I have ever gotten spellcraft against that ogre...

As for spells, usually it just casts these: Earthquake, Gate, Destruction before switching to the harm type of spells. (The last time I died to this boss, the destruction spell DC was 22, and I rolled one...)

[Valefort]

Energy drain could have critted as well, from the combat log your character made two attacks at 16 and 11 AB. Maybe you can deduce what happened from just that ?

[Sun Wukong]

I think I had Northlander Hewing on alongside with rage. So yeah, if the spell did crit and took away 15 levels, then my current AB would drop down to those numbers. But the initial Energy Drain roll would need to be 7.5 to get that right?

Other explanation is that those were just tail end of a regular attack flurry, if I forgot to turn on the Northlander Hewing. (Those ogres have low DR, so I do not have it on by default... I only tend to turn it on against the casters to increase my chances of disrupting their spells, as more damage makes it harder to roll concentrate.)