Magic Item

Artifacts of Gate keeping
OMG this gives me an idea for a funny magic sword
The Gatekeeper
This is a talking sword/whatever that gatekeeps your achievements in combat and lets you know how insignificant your efforts are, very often. It can be impressed only by three things:
1. Killing an enemy of difficulty higher than your own as the past party member standing while you are on your last 1 HP.
This gives the sword a +1
2. Reaching mastery (level 20)
This also gives the sword another +1
3. Killing a (insert random "max DC" enemy at least remotely relevant to current campaign)
For a +1
When you collect all 3 bonuses, the weapon loses its ability to gatekeep you from your combat achievements and becomes a "standard" magic +3 sword/blade/whatever.
Additionally it could also have the ability to open a magical gate to a plane composed solely of a magic room in which you have a decent sized vault, a treasure trove, you had to fill. Doing so would give the sword another +1.
The sword would only gatekeep your riches.
"Pfft, that's nothing, have you seen the treasure of (insert someone richer than the PC)? Now that's what I'd call a treasure!"
"At this rate I'll catch rust before you find enough treasure to fill this trove"
"Are you actually trying to find anything valuable, or are you just collecting baubles?"

/r/DnD Thread