After 18 months of playing Second Darkness our heroes are finally ready to take the fight to the drow. They've skirmished with the dark elves before, but avoided the major battle at the end of Book 2 when they inadvertantly stumbled into the drow lair and had to retreat. The drow then escaped under the cover of night while sending a shadow demon to kill them.
Now though, it's war. After a sustained interlude of dragon slaying and ogre hunting we've begun Book 3: The Armageddon Echo, which sees the heroes travelling to the village of Crying Leaf to join the surface elves in waging war against the drow. Their goal? The liberation of the ancient, ruined elven city of Celwynvian.
Up until this point in the campaign I've been able to get away with using existing NPC statblocks from various Pathfinder source books, updated monsters from the Bestiaries, and the occasional on-the-fly conversion of an NPC statblock. With Book 3 though I find myself finally need to rebuild statblocks from the ground up.
While I could continue to adjust things on the fly, we've reached the point where the 3.5 statblocks in Second Darkness are feeling dated. The drow, which always have character levels, don't have all of the cool new class features introduced in Pathfinder. That makes them underpowered relative to the heroes, which means I can either re-build them or throw more of them into the fight. None of the 3.5 statblocks have combat manuever bonuses or combat manuever defenses calculated, hit points are generally subpar and some rules -- such as how spell resistance is calculated for drow -- have seen big changes.
Thus I find myself on a Sunday listening to R.E.M.'s "It's the End of the World As We Know It" (entirely appropriate, given Second Darkness's apocalyptic plot line) while building out drow.
I'm aided in this by Yet Another Pathfinder Character Generator. The most recent version of the tool -- 5.2 -- incorporates drow stats from the Ultimate Race Guide. I'm mostly using it as a gutcheck on my own conversions; its easy enough to quickly work through a stat block and figure out what the Pathfinder equivelent is, but YAPCG helps ensure I'm not missing any feats, talents, or class abilities. It also simplifies updating skills for the new edition.
When converting NPCs I try and keep things as simple as possible. I favor additional hit points and skill points over spells, as the former is easier to keep track of. With bonus feats I pick options that augment existing capabilities -- saving throws, weapon attacks -- rather than introducing new options. For named NPCs I might spend more time on options, but honestly most of these drow won't live long enough to use the capabilities they already have. Why give them more?