I'm making one of these for a home game. The archetype's adjustments are simple:
1. Shadow callers must be fetchlings
2. Summoned creatures normally receiving the celestial or fiendish template instead recieve the shadow template. Specific outsiders are replaced by shadow-themed replacements (i.e. cloakers, kytons, shadow undead, etc.)
3. Recommendation for Shadow Blend and Shadow Form evolutions.
I'd like some advice for making the eidolon, perhaps spells? My concept is a roguish character, hiding in shadows (has some rogue levels) with shadow powers. Summoner level 5
Firstly, avoid the rogue lvl. They are a let down, whether you optimise or not. You will be stronger and more effective if you stay in Summoner, even when you go in melee .
You could build like this, seeing tha you intend to go close and personal too.
Fetchling Shadow Caller Summoner 5
1 Arcane Strike
3 Resilient Eidolon
5 Power Attack
Alt. racial trait: Gloom Shimmer
Favored class bonus every lvl.
Evolutions (8p): Claws (1), Pounce (1), Tentacle (1), Shadow Form (2), Shadow Blend (2), Improved natural Armor (1)
Eidolon feats: Toughness, Power Attack
You should aim for more limbs and claws, as well rend, ability increase (str), energy attacks and INA.
You should flank the enemies with your shadow.