D&D 5E (2014) I'm the DM and a player is trying to abuse the Immovable Rod. Advice?

[Tony Vargas]

This is pretty much entirely wrong. You can use it, sure, but it's not historically correct at all.

'Historically correct' is even weirder.

 

[jgsugden]

When a character has an object and the game is made more difficult by the presence of that object, an NPC thief is about to have a very good day.

That being said, there is a lot of slow and plodding ways to abuse an immovable rod, but they're not really abuse. They're use of a versatile magic tool. Allow the player to have fun, following the rules, when using it. If it becomes a signature move of theirs to make use of it in interesting ways: Good. That is the point of the new magic item rules in 5E - to make every magic item iconic and fun rather than just being a thing you plug onto your MMO-esque character.