Tenser's Tapping Stick
The 10-foot-pole is one of those weird artifacts left over from the original days of D&D. Given the way the game is played today one could be forgiven for not understanding why such a mundane and unwieldy object finds itself in the 5e Player's Handbook adventuring equipment section. Listed simply as "Pole (10-foot), 5 copper, 7lbs" the pole doesn't even get its own description in the more detailed explanation of some adventuring gear. In fact, the only other mention of a 10-foot pole in the PHB is on page 190 where it is mentioned that tapping a 10-foot pole counts as a type of incidental action not requiring an action (like opening or closing a door).
In the old days of Dungeons and Dragons, long before the coming of the 3rd age and the d20 system, skill checks weren't a thing. Traps were dealt with on a less game mechanical basis and tended to have their mechanisms described in clearer detail. For player's to get past these traps, a great deal of careful poking and prodding could be helpful. The first edition of the game is also notorious for its insta-death traps, deadly caustic slimes lurking out of sight, spheres of annihilation casually hanging out in statues, etc. Hence the 10-foot-pole was found to have boundless uses for the first wave of players in the game.
Due in part to 3rd edition and its "disable device" skill, this style of playing out traps fell out of favor with gamers who didn't want to tediously tap their way forward to avoid trip wires. I think 5e further improves on the streamlining of traps in gameplay with the addition of passive perception to avoid exactly that type of scenario.
And even though I began the game in the 3rd edition era and never dealt with much 10-foot-poling myself, I do have a soft spot for gaming traditions. To honor that tradition and to further play around with the D&D beyond homebrew tools, I bring to you my first spell to be added to D&D Beyond.