I'm asking myself if the eidolon of a synthesist actually takes damage.
While fused with his eidolon, the synthesist uses the eidolon’s physical ability scores (Strength, Dexterity, and Constitution), but retains his own mental ability scores (Intelligence, Wisdom, and Charisma). The synthesist gains the eidolon’s hit points as temporary hit points. When these hit points reach 0, the eidolon is killed and sent back to its home plane. …
The rule states, that you get the eidolon hp as temporary hp. However, it is not directly mentioned, that the eidolon takes damage. Instead, your temporary hit points are reduced.
I'm sure that I'm misunderstanding something, as this would imply letting the temp hp drop to 1, dismiss the eidolon and summon it, gaining its hp (still unchanged and in full) as temp hp. It is implied, that the eidolon takes damage by lowering the temp hp, but does it keep this value as its actual hp?
Best Answer
Yes
Note the particular wording of what you've quoted from the synthesist archetype, "The synthesist gains the eidolon’s hit points as temporary hit points."
Those temporary hit points are the eidolon's hit points, so the missing would still be gone if the summoner dismissed then re-summoned the eidolon per the standard rules for eidolons.