I love the Lovecraft. For homegames, there was a 3.5 mage sourcebook, that added a template to summons for this sort of feel. I looked it up Tome of Blood PrC Alienist.
Here is a verision of it for PF not official
http://www.pathfinderdb.com/character-options/prestige-classes/779-alienist
There are some PF classes that hold a some of the feel Aberrant sorc, oracle of heavens.
For Summon Spells, I would see if your GM would allow you to add templates to your summons, dropping down a spell of the summons and applying whatever CR changes appropriate.
Hounds of Tindalos... Good times, I Gm'd a game with them as monsters the surprise was when a ranger used fly to escape from a couple and they flew after them. I cannot recall if I used a source book or created them.
Well, almost.
The guide to PFS includes material from the various articles on the gods of golarion in the pages of the adventure paths, and nearly all of them have modified summon lists, mainly adding in deity appropriate beasties at 2 or 3 levels.
I have been wondering if, with summon monster, you can only summon what is on the list already. I mean, what with their being a bestiary 2 now and everything I was hoping there would be rules for summoning something not on the list. Perhaps stuff like the Hounds of Tindalos and whatnot. Mainly wondering due to being a huge Lovecraft fan. I have always thought characters of some faiths or making really obscure knowledge checks should be allowed some special summons.
Bestiary 1 is all you get. They won't really be updating the list because they don't want there to be too many choices. I do think some of the other books such as the AP's have options.
Well, almost.
The guide to PFS includes material from the various articles on the gods of golarion in the pages of the adventure paths, and nearly all of them have modified summon lists, mainly adding in deity appropriate beasties at 2 or 3 levels.
Could you tell me which books may have that stuff? Because I am running a pirate cleric of Besmara in Jade Serpent Skull and a Dhampir cleric of The Old Ones in Carrion Crown.
I think the book gods of golarion is the one you are looking for.
Also some AP books that have more/revised info about gods and what they offer, for example the 2nd book of Kingmaker has info about Erastil and his followers.
To my knowledge, there has not been an article on either Besmara nor the Old Ones, thus no customized summoning list.
Could you tell me which books may have that stuff? Because I am running a pirate cleric of Besmara in Jade Serpent Skull and a Dhampir cleric of The Old Ones in Carrion Crown.
Every 3 AP volumes (#2, #5, #8, and so on) has an article on one of the Golarion deities. Some of these articles include customized summon lists, but not all.
Besmara and The Old Ones don't have such an article yet (they're not even quite done with all the major deities at this point), so they're so far out of luck on customized summons.