So I am looking to PrC a summoner as a mystic theurge and while I understand that when you level as a Mystic Theurge you don't get any of the special abilities or bonuses listed, but you do get the spells.
With that said, the Eidolon specifically says it's evolution is based on the the summoner "class level" and the Mystic Theurge grants a "+1 to existing level of a arcane/divine class". It seems a little ambiguous so I would love to get the feedback of the community.
Obviously druids and rangers also fall into they category of a pet the is dependent on its advancement via the PC's "class level" - so the general consensus would apply to them, I think.
Thanks!
"+1 to existing level of a arcane/divine class" is for spells only. Eidolon does not advance with Mystic Theurge.
Mystic Threurge does not increase the "class level" for the summoner. It increases the caster level for that class. The pet is not influenced by caster levels. As an example an Orange Prism ioun stone grants additional caster levels for a class, but it won't make the pet any stronger for a class.
Got it. I think my brain is melting with all the ven diagram rules sometimes.
The Boon Companion feat can be used to help here, but you still won't be able to advance your animal companion beyond pet class level + 4. At least a familiar still gets half of your hit points regardless of what class those hit points come from.
Even that won't help a summoner, though.
Even that won't help a summoner, though.
That does go along with how I have always thought of the Summoner as a "pet" class -- it is the summoner spellcaster that is actually the pet. At least, that is what most eidolons would say.
But it is clear that if you have a class feature that is actually at least as valuable as your spellcasting, you probably don't want to enter a prestige class. A summoner would probably balk even at the one level loss for the Evangelist.
It would certainly not be unreasonable to house-rule a form of Boon Companion to allow for scaling by eating feats, but that would be a house-rule. As-is, the previous posters are right. If you look at the top of the table that gives +1 arcane/divine class, it says "Spells per Day." Only your casting is augmented by PrC, making multi classing with a summoner a poor choice, generally.