Arcane Bloodline Familiar: Spell Catalyst (Su) - Spells you cast that target your familiar are treated as having a caster level 2 levels higher than your actual caster level.
So... Hypothetically speaking - if Mr. Crispy (the Familiar) moves into the enemies square, and is subsequently hit by my fireball, what happens?
A) The Spell is AoE and isn't "Targeting" so nothing happens.
B) The Caster Level is increased only against Mr. Crispy and the other targets in the AoE are affected normally.
C) The Caster Level is increased for all targets of Fireball if Mr. Crispy is in the AoE when it is cast.
Obviously, this Strategy is only going to be used on Fire Resistant familiars or Figmented Archetype familiars - to prevent Mr. Cripsy from a preemptive death due to his master exploiting him for "target" practice. But does this work at all?
Fireball is an area spell, not a target spell, and thus would not benefit. This is an edge-case since the word "target" is often used informally throughout the rules to describe situations where a create is within the area of an area spell, but in this case I would require the spell to formally be a target spell rather than an area spell.
This still opens up the case of spells that can have multiple targets including the familiar, such as Communal Protection from Evil or Mass Suggestion. That would be up to GM discretion as to how it worked in such a case. I think in most of those cases all it would do is raise duration and help with SR so I'd be inclined to allow it to raise the caster level of the spell for all targets.
Given that a fireball explodes normally for other people around if the target's Spell Resistance isn't bypassed, I'd say it is case A.
Now imagine a case where a harmful spell targets a set number of creatures in an area of effect in a way that isn't at the discretion of the spellcaster and the familiar happens to be in said area. I think Sleep works this way. What then?
Hm... I'm not too magically inclined in Pathfinder, so I do not know the benefits of the Arcane Bloodline familiar then. I'll probably as the Advice threads to see what they thing. lol
Though - it seems like a Multi-target spell targeting the Familiar and another target would also work? Sadly, most of the fun damage spells are Ray-Attacks, which increases with every 3 levels instead of 2 levels.
The bloodline familiar powers are fairly weak to begin with, so it’s not supposed to do much. In general, it just allows the buffs you cast on your familiar to last longer, but there are other possible combos.
The big selling point of having a bloodline familiar is simply having a familiar. The bloodline part is just a bonus.
Arcane is pretty funny, because you are trading its ability to get a familiar to instead get a familiar with an extra perk. It’s kind of a no brainer. Especially since the bonded object option doesn’t work well without a spellbook.
Having a Bloodline Familiar also delays your bloodline spells. And Arcane has one of the best list of bloodline spells in the game, so you're going to be missing out on a pretty good spell at your highest spell level a lot of the time.