In our last session, the party was in a large ice cavern which the adult white dragon boss monster was attempting to enter through a tunnel that was just wide enough for itself. The party evoker had placed an Arcane Hand, set for "Interposing" just inside the mouth of the tunnel to prevent the dragon from entering the larger space and being able to make use of its fly movement, better targeting of breath weapon, etc.
The "Interposing Hand" says:
The hand interposes itself between you and a creature you choose until you give the hand a different command. The hand moves to stay between you and the target, providing you with half cover against the target. The target can't move through the hand's space if its Strength score is less than or equal to the hand's Strength score. If its Strength score is higher than the hand's Strength score, the target can move toward you through the hand's space, but that space is difficult terrain for the target.
Since the Hand's Strength is 26, and the dragon's is 22, the dragon "cannot move through the hand's space".
However, could the dragon attempt to push the Hand back a space, and then move forward into the space the Hand had previously occupied?
The Hand is explicitly an object. This question (thank you @Thomas Markov for the link) asks whether it can be Shoved as if it were a creature.
The accepted answer there says that because it is an object, it cannot be Shoved, but does not suggest how it then might be moved as an object.
An alternate answer there agrees that it cannot be Shoved since it is an object, but then clarifies that an attempt to move it as an object should be resolved 'the same as a Shove attempt against a creature'.
So that this question is not a duplicate of the referenced one, let's agree that the Hand cannot be the subject of a Shove attack per se because it is not a creature (if you disagree, you should post an answer to the other question).
Since the hand is an object, can it be moved by a push as an object?
Should I read the "the target can't move through the hand's space" as a specific over general prohibition against any kind of pushing attempt from the target (but perhaps not from the orc minions of the dragon),
or as a specific over general exception so that the Large Hand only prohibits the movement of Small and Gargantuan creatures through its space, which it otherwise would not do?
If the Hand CAN be pushed, how should this be resolved?
If the dragon is permitted to push the Hand (or if not, when the dragon's minions attempt to move it instead), can the Hand simply be moved as an object, automatically but subject to the rules about weight limits when pushing an object? Spells do (only) what they say they do, and nothing in the spell description explicitly gives the Hand the ability to resist being moved, especially by creatures that are not the target.
Or should I read "The hand interposes itself between you and a creature you choose" as giving it the ability to actively resist being moved, such that any attempt to move it must be resolved in the manner of a Shove attack and it can use its Strength score to make an Athletics check even though we acknowledge it is not a creature?
Best Answer
There is nothing to push against
The paragraph describing the hand's characteristics includes one critical sentence, which I have highlighted in bold below:
This means that you can't push the hand because if you push against it, you just go right through it instead!
Interposing Hand doesn't enable the hand to be pushed
Somewhat counterintuitively, Interposing Hand doesn't actually modify the above rule:
Thematically, an interposing hand impedes the target from "pushing" past the hand by pushing back at them. However, mechanically, there is no mention of pushing. Instead, Interposing Hand restricts the target's movement, by either making the hand's space impassible or difficult terrain, depending on the target's strength score. There is nothing in the text of Interposing Hand that allows the target to push the hand.
In summary, the hand's description does not give any way to push it, and none of the effects caused by the hand modify that in any way, not even Interposing Hand.
Incidentally, note that the effects of Interposing Hand apply only to the target. All other creatures can still move through and occupy the hand's space without impediment, which underscores the fact that even while the hand is interposing, there is (mechanically) nothing to push.