restore eidolon as a synthesist?

[kinderschlager]

since you and your summon count as a single creature is it able to affect ability damage for all ability scores?

[Melkiador]

There’s a FAQ

Quote:

Summoner: What happens when a synthesist (page 80) takes ability damage or drain while the eidolon is present?

The eidolon takes Str, Dex, and Con damage or drain, the summoner takes Int, Wis, or Cha damage or drain. If this bring's the eidolon's Str or Dex to 0, the fused summoner/eidolon is helpless (though he can still dismiss the eidolon). If this brings the eidolon's Con to 0, it dies and returns to its home plane. If the eidolon goes away (whether dismissed, banished, or killed), the summoner immediately begins using his own Str, Dex, and Con.

There is no "spillover" for extra ability damage or drain beyond what it takes to reduce the eidolon to 0; if an eidolon with Constitution 1 takes 3 points of Con damage and dies, the summoner doesn't take the "extra" 2 points of Con damage. However, ongoing effects (like continuing poison damage) would affect the (non-fused) summoner after the eidolon disappeared.

Remember also that the eidolon does not heal naturally. Just like hit point damage, any ability damage or drain the eidolon has persists between when it is banished/dismissed/killed and when it is resummoned. The exception is an eidolon killed by Con damage (which, if resummoned, would still be at 0 Con and immediately die and vanish); in this situation, the resummoned eidolon is cured of 1 point of ability damage or drain so the amount of damage or drain is 1 less than its actual Constitution score, allowing it to live.

Effects that cure ability damage or drain work on the eidolon's ability scores when it is summoned.