The Unseen Servant spell creates
…an invisible, mindless, shapeless force…
…It has AC 10, 1 hit point, and a Strength of 2, and it can't attack. If it drops to 0 hit points, the spell ends…
This shapeless force has a strength score and can interact with objects, including carrying them. It can take damage, though what forms that damage take are left unspecified. Does this mean an Unseen Servant can be physically manipulated and interacted with? Here are a series of related sub-questions:
1) Can an Unseen Servant be picked up, shoved, carried, or pushed aside?
2) Can it be commanded to "ride" or "hang on" to another willing character (such as the party fighter) as a means of allowing it to keep up with a group moving faster than 15ft a round?
2b) If so, does it have weight?
3) Can an Unseen Servant displace water, fog, and other substances?
3b) If so, can it be used to create a small "window" in fog, allowing a character in fog to see through the servant to a space without fog?
3c) If it does displace other materials, could careful observation of this phenomenon allow a character to "spot" an Unseen Servant?
Best Answer
Let's dive into this spell a bit.
Unseen Servant
Now that I've enforced the relevant sections of the text; we can start to answer your questions.
Can an Unseen Servant be interacted with?
Can it be commanded to 'hang on' or otherwise interact with another creature?
Can Unseen Servant displace substances?
In closing; this is one of the very few spells that leaves me with holes in it's logic. It is invisible. This one is easy enough. If it DOES possess some sort of form, then you can not see it by mundane means. It is mindless. Possessing of no intelligence or mental acuity, and so it can only follow commands to the best of its abilities, which are very poor and extremely under your average human beings range of capabilities. It is shapeless. This is where the most confusion appears. Possessing of no shape, no substance that comprises it's physical being; whether invisible or not. If it has no shape, yet occupies a space on the ground, how does it interact with the items it must interact with in order to do it's job as per the spell permits? I can't logic this one away. 'Magic' seems to be the only thing holding this together.