After reading the Bestiary 5, this seemed like a good idea: an archetype for the summoner that's based around the creation of a tulpa (tulpas are creatures produced from the imagination of powerful minds, they can have any shape/alignment, and are sustained by belief).
Tulpa Master(summoner archetype)
Eidolon(su): The Tulpa Master's eidolon receives the tulpa template (B5, p.254), but the eidolon can only use innate tulpa spell-like abilities of a level equal or lower that the summoner's class level.
Spellcasting: The Tulpa Master uses the mesmerist spell list and is a psychic caster.
Channel belief(su): The Tulpa Master can heal himself or his eidolon as a swift action. This works as the spell Cure Light Wounds. At 3rd level this works as Cure Moderate Wounds, at 5th level as Cure Serious Wounds, at 7th level as Cure Critical Wounds, at 9th level as breath of Life, and at 11th level as heal. This ability can be used 3+ charisma modifier times/day. This ability replaces summon monster.
Share belief(su): By spending 10 minutes in attunement with a creature or group of creatures up to 1+summoner's charisma modifier, the Tupla Master can allow the creatures to heal the eidolon whith the tulpa ability sustained by thought(su). Those individuals can also be affected by the Channel Belief ability as if they were the eidolon.
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As an alternative to the Synthesist, I would do the following:
Tulpa Ascendant:(summoner archetype)
Created Self Image(su): The Tulpa Ascendant receives the tulpa template (B5, p.254), but he can only use innate tulpa spell-like abilities of a level equal or lower that the summoner's class level. He cannot use the Mental Form (Su) ability. He is considered to be his own creator, and receives all the benefits an eidolon would receive from his levels, including evolutions, natural armor, str/dex bonus and abilities, but not HD, Bab, save, skills and feats. The Tulpa Ascenant is affected by effects that target outsiders and his original type. This replaces Eidolon.
Spellcasting: The Tulpa Ascendant uses the mesmerist spell list and is a psychic caster.
Channel belief(su): The Tulpa Ascendant can heal himself as a swift action. This works as the spell Cure Light Wounds. At 3rd level this works as Cure Moderate Wounds, at 5th level as Cure Serious Wounds, at 7th level as Cure Critical Wounds, at 9th level as breath of Life, and at 11th level as heal. This ability can be used 3+ charisma modifier times/day. This ability replaces summon monster.
Share belief(su): By spending 10 minutes in attunement with a creature or group of creatures up to 1+summoner's charisma modifier, the Tupla Ascendant can allow the creatures to heal himself whith the tulpa ability sustained by thought(su). Those individuals can also be affected by the Channel Belief ability as if they were himself.
Shielded Image(su)At 4th level, whenever the Tulpa Master is within 30ft. from a creature under effect of shared belief, he gains a +2 shield bonus to his Armor Class and a +2 circumstance bonus on his saving throws. These bonus increase to +4, and the radius to 60ft. at 12th level. This ability replaces shield ally, greater shield ally and life link.
Mind's Reach(su): At the 13th level, the Tulpa Ascendant may add teleport and planar shift to his spells known list and class list. This ability replaces maker’s call and transposition.
Memory of Life(su): At 16th level, as long as at least one creature that was subject to share belief is still alive, the Tulpa Ascendant can return to life once per day as if subjected to a True Resurrection spell.
Thoughts?
Well I love it. I especially love the Tulpa Master, that is crazy awesome. I haven't looked at the Bestiary 5 yet but this seems like the right direction for a psychic summoner.
I'm not sure if I should love the Tulpa Ascendant, but I do. Memory of Life is amazing.