So one of my players is wanting to build a synthesist. After having made and tried an NPC of the same archetype previously, I was wondering if there could be a few moderated nerfs put into place to adress some of the most blatant problems with it.
So I had the following idea:
The Strength and Dexterity score of the eidolon's base form cannot exceed the summoner's score by more than 2. For example a Synthesist with Str 10 and Dex 12 would have a bipedal eidolon with base Str 12, and Dex 12 or a quadrupedal or serpentine eidolon with Str 12 and Dex 14.
Additional Strength bonuses from evolutions, ability score increases from hit dice, Str/Dex bonus gained through summoner levels as well as outside sources such as magic items, spells, etc. can exceed this limit as normal.
If the summoner has more strength or dexterity than the eidolon this has no additional effect, you simply use the eidolon's strength.
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The intention: prevent synthesists from dropping their physical abilities through the floor, if you want to be especially strong, you will still have to invest in strength and can't just let the eidolon take all of it. At the same time you can't max out your strength beyond what a regular eidolon can already do.
I was also thinking Improved natural armor can only be taken on levels 1, 8 and 15, because eidolons already have enough AC, and when I tested the NPC only the orc barbarian who pooled all of his build points into Strength could hit it reliably (well and the witch who had a couple of touch spells).
My recomendation is to turn the eidolons physical ability scores into a bonus as opposed to a replacement. And set the base as a 12. So at 1st level, the biped gets a +4strength, +1 con, the quadraped, +2 str, +2 dex, +1 con, the serpentine +4 dex, +1 con when in their fused form.
As the summoner goes up in level and with evolutions those numbers will increase.
But in general the best fix for a summoner and the synthesist in general is to force him to divide their evolution points between combat power and utility. The problem with the summoner isnt how much stuff you get, its that they get to choose each and every thing they get. So with relatively little effort they come out super optimized if the person simply chooses all the options that help them do whatever they are optimizing. Even the druid gets stuff like wild empathy, or trackless step. Forcing the summoner to put at least a third of his evolution points into stuff like skilled, or blindsense makes a huge difference in its relative power level.
That is sound advice. I will keep that in mind.
So one of my players is wanting to build a synthesist. After having made and tried an NPC of the same archetype previously, I was wondering if there could be a few moderated nerfs put into place to adress some of the most blatant problems with it.
Start at a higher level like 9.
By then a synthesist is a summoner with a better will save and half their actions.
We're actually at 11.
We're actually at 11.
Then I wouldn't worry. Just make sure the eidolon is legally built.
Limit the number times a synthesist can have the arms evolution to once per ten levels, or so.
I don't see that as being a problem. Natural weapons still have their own limits and multiweapon fighting is a mighty unimpressive feat.
Well so far the eidolon looks as follows
Bipedal
Flight (magical, speed increase) 5
Strength increase 2 (I have to get back to him on that, as I only remembered later that this evolution is more expensive for large eidolons)
Blindsense 4
Large 4
The summoner has Power attack, exotic weapon proficiency katana, improved crit (katana), combat casting
and i forgot the other two feats, but altogether nothing too serious. Also he went the honorable way and spent some points on dex, playing a kitsune. His eidolon will have the shape of a giant floating samurai in armor.
So I don't think he will be an extreme powerhouse of any sort.
I don't think you need house rules on this. There are already large built in limitations on the summoner (and especially synthesist) that in practice will slow him down a great deal. The most obvious is that he is vulnerable when not his giant hulking monster, and going around as a giant hulking monster in many circumstances is not going to be ok.
Just being Large means he won't fit into a lot of spaces. If he wanted to optimize it, he'd get Large from evolution surge.
Large creatures fit just fine in most places, really. They have a problem with doors (need to squeeze for human sized doors) but once inside there shouldn't be much issue, especially when dungeon crawling (since many nasties are also Large size or have Large sized minions).
It's Huge that is pretty much nonfunctional in tighter spaces.