What does the Orb of Time actually do?

Question

Printed in Xanathar's Guide to Everything on page 138, the magic item Orb of Time has the following description:

Wondrous item, common
Minor tier
3 lb.
While holding this orb, you can use an action to determine whether it is morning, afternoon, evening, or nighttime outside. This property functions only on the Material Plane.

During a PvP one-shot, I pulled this object out of my pocket, as the one Common-quality Magic item each player was entitled to, and declared "I use my action to make it midnight!", expecting that the sudden loss of sunlight would confer advantage to one of my Shadow Blade-wielding rivals (whom I expected would be easier for me to fight than the opponent she was up against).

My DM then informed me that that wasn't how the item was meant to work, and we had a laugh about how my character believed that that's how the item worked and so just assumed from the [lack of] outcome that she was not on the Material Plane.

^{She's 800+ years old with an Intelligence of 8, it's entirely in character that that's what she would think it would do.}

But, it begs the question: which of us were actually right? Is the Orb of Time capable of literally changing the time of day, or is it a glorified pocketwatch?

Answer 1

It's a watch.

An imprecise watch.

An imprecise watch that only works on the material plane.

5e's goal is to use natural language, specifically. You've quoted precisely what it does:

you can use an action to determine whether it is morning, afternoon, evening, or nighttime outside.

"Determine" is the sticky wicket here because it can mean "cause to be" or it can mean "ascertain". Being able to control time has enormous ramifications in and out of game, so the Orb of Time wouldn't be that powerful and reasonably still be a Common item.

P.S.

For more information as to why an imprecise watch would be considered a wonderous item, from the Sword Coast Adventurer's Guide:

Most people don’t keep track of the time of day beyond notions such as “mid-morning” or “nigh sunset.” If people plan to meet at a particular time, they tend to base their arrangements around such expressions.

The concept of hours and minutes exists mainly where wealthy people use clocks, but mechanical clocks are often unreliable, and rarely are two set to the same time. If a local temple or civic structure has a clock that tolls out the passing of the hours, people refer to hours as “bells,” as in “I’ll meet you at seven bells.”

Despite being imprecise by today's standards (which didn't become standard until the 1880s), and unable to solve some of the problems of navigation, if you are mining or exploring underground, being able to tell and keep time precisely enough without any natural cues becomes incredibly useful.