Nagafen Strikes YOU
 

Trying to tune the encounter with Nagafen and he strikes for 500. Tried taking away enrage but that wasnt it. Anyone know what this attack is and how to change it? Was able to find a table for the NPC special attacks but not the special abilities. Wondering if anyone knows what those are also.

That's a nuke spell Naggy has. Actually, kind of like a proc. npc_spells id 25
EDIT: Sorry, guess I should be more specific for others. It uses spell id 861 (lava breath) It shows the 861 entry in npc_spells_entries, (using this for example), so when you want to look something up in the future.

Still having an issue. Can the 500 damage be altered somehow?

I guess it depends on what you want to do with it ? Remove it, decrease damage, or increase damage ?
To increase or decrease damage, spells_new table, 861. you will see the -500 under the effects_base_value1 column.
To remove it totally, simply take it off Naggy's spell list. Just keep in mind, if you edit that 861 spell, others like Vox use it too.

Thank you sir, that was the thing we needed.