I have never used Summon Servitor, but I do not intend for this review to be based on the concept of actually playing the card and utilizing its ability to perform as a remote agent. I'm sure there are some interesting edge cases, something something Luke Robinson, but I haven't explored those possibilities of this card, though perhaps one day.
What I am here to comment on is that this card lets you do something oddly specific that is very hard to find: Return an asset of ANY kind from your board to your hand. Rogues can do this with Item assets in several different ways, Scavenging can pull items from your discard, and William Yorick can play any type of asset from his discard. But there aren't many ways to remove literally any asset from your board, with no restrictions on level, class, or type.
Why does this matter? What's so important about the ability to put ANY asset (besides weakness/permanents) back into your hand? Well, we can start with the above Luke and his Gate Box. Replaying it is a way of recharging it, although if you're spending 3 XP and 2 card slots you can do way better. There are plenty of ways to place charges/secrets/ammo/supplies on cards, and they'd all do a better job than this card. But consider for a moment things that DON'T use those kind of resources, and instead use weird ones you can't refill. Think about:
-Daisy Walker and her Archive of Conduits
-Dexter Drake/Sefina Rousseau wanting to cheat their Geas a little bit
-Building around Hyperphysical Shotcaster as a Mystic and not having access to Rogue or Survivor level 0 cards.
-Father Mateo wanting to get a couple extra uses out of The Codex of Ages
-Sister Mary trying to repair her Guardian Angel
Okay, ya, those are all the use cases I could find, and they aren't a lot, and the only one that seems all that decent to me is the first one. But there's a LOT of potential here depending on future investigators/assets that are released.