HELLO I'M KIWI
This is where I write things.
Woundrous Item, rare
Lymere was a devout Celestian monk who traveled for decades with the aim of uncovering the many magical gates hidden across the lands. These wraps she wore during her expeditions are said to hold an echo of every portal she passed through.
While you’re wearing these cloth wraps, your unarmed strikes are considered magical for the purpose of overcoming immunity and resistance to nonmagical attacks and damage, and you gain a +1 bonus to the attack and damage rolls of your unarmed strikes.
Once per round when you make an unarmed strike, roll a d20. If you roll a 1, roll on the Portal Surge table to create a portal effect.
Roll a d4 to determine the target's new form:
Roll a d4 to determine the duration of the polymorph:
† Effect lasts for 1 minute or until you roll another Portal Surge.
I made these wraps for the Monk player (N) in my Sunday 5e game. N was looking for something to beef up his Goblin Grandma, Surmaputk, and so I told him to throw a couple items my way that he was interested in picking up. I don't do magic shops, per se, but the party was fresh off saving the city and collecting a dragon's hoard, and they'd made the sort of connections that could get them some rare items in our very-magical homebase city, so it felt timely.
The Dragon Hide we was looing at was alright as is; I knew Wyrmreaver Gauntlets wouldn't fit the game; and the last would work fine, the Wraps of Unarmed Prowess, but it was just so... basic. And N is anything but basic.
I sent him the base item information, and I got to work on the table. Some GMs may prefer, or may even think it pertinent, to have a whole huge list of results at the ready, right off the bat. Myself, I'm a big proponent of only prepping what you're likely to need, so I started with only four results, and would add more results each session or as it felt appropriate, such as when the party started doing some planar traveling of their own. Some of the list items are pretty standard fare, a little extra damage of a particular flavour, an extra bonus to hit, etc. But others, I want them to be weird. My favourite is probably the Exhaustion effect -- just thinking about how much a few temporary levels of Exhaustion could change a big fight scratches my brain in a fun way.
So, is this balanced? And how does it play out at the table? I don't know, honestly. As of the time I'm writing this, we haven't seen a portal surge happen yet. Even when I artificially inflated the chance of one happening, N just could not roll a 1 on the die. We're in the final third of our campaign (#41 out of 60 sessions max), with a non-zero chance of battle, but a lot of RP in the foreseeable future, so I don't know if or when we'll see this item fully activate before the end of the game. If it DOES activate, I'll update this article or do a follow up. And of course, I'll update the Portal Surge table if it becomes a full d20 list.