Invisibility items
I made this document, because both the cloak and ring of invisibility are quite limited in how much play they can see. They are legendary items for good reasons, but within reasonable limits they could easily be rare or very rare items, making them available at lower levels, without DM's and players fearing they might break their game.
The original ring is unlimited in how often you can use it and how long you can stay invisible, definitely influencing its power level. Since only attacks and spell casts break the invisibility, one could feasibly live their lives invisible. Now, even though that mind sound awfully powerful, and it is, it's not all that useful to a PC to be invisible all the time. However, the idea that it can be used however many times one likes is very powerful, indeed. That being said, the cloak is limited to two hours with a 12 hour recharge time per hour, which is much more reasonable, but it is still legendary rarity.
Art credit: Robson Michael, "Sheila, the Thief"
https://www.patreon.com/Chubby_Alpaca
Compared to other magic items this inconsistency becomes more clear. As the effects of the items are broken by attacks and spell casts, the effect isn't greater invisibility and invisiblity is only a 2nd level spell. Meanwhile, an item like Necklace of Fireballs casts several fireballs, a 3rd level spell and a good one at that. While invisibility seems like an extraordinarily strong effect, compared to some others, perhaps later designed, magic items (notice the unusual structure of the mechanics of both invisibility items, hinting at being some of the first items created for 5e), the only thing that warrants the rarity of these items is the duration of the effect and the removal of the concentration requirement. Certainly there is also a factor of shared history, with the ring being reminiscent of the One Ring, but this should perhaps not factor in too much.
So, the goals here are the following: Firstly, limit the amount of uses and secondly, limit the timeframe. Surely, this is a very easy conversion, but to make it just a little bit more interesting, we'll add some more flavor to the items while achieving these goals.
Ring of Invisibility
Ring, uncommon (requires attunement)
While wearing this ring you can turn invisible as an action. Anything you are carrying or wearing turns invisible with you. You remain invisible for 1 minute, until you attack or cast the spell, or until you choose to become visible again, no action required.
You can use this item once, which recharges at midnight.
Slayer's Signet
Ring, rare (requires attunement)
While wearing this ring, you can turn invisible as an action. Anything you are carrying or wearing is invisible with you. You remain invisible for 10 minutes, until you attack or cast a spell, or until you choose to become visible again, no action required. When your invisibility is broken by a melee weapon attack, you gain advantage on both that attack roll and its damage roll, if you hit.
You can use this item once, which recharges at midnight.
Cloak of Invisibility
Wondrous item, uncommon (requires attunement)
While wearing this cloak you can pull the hood up and turn invisible as an action. Anything you are carrying or wearing turns invisible with you. You remain invisible for 1 minute, until you attack or cast the spell, or until pull the hood down, no action required.
You can use this item once, which recharges at midnight.
Cloak of Cloaking
Wondrous item, very rare (requires attunement)
While wearing this cloak, you can pull its hood up as an action, extending a cloaking field centered on you with a 10ft. radius. When you activate the cloak, you can designate up to four creatures that are affected by the field. While affected by the field, creatures, including you, and anything they are carrying or wearing turns invisible. The field lasts for 1 hour, until any of the affected creatures attacks, casts a spell, or you end the effect by pulling the hood down as an action on your turn.
You can use this item once, which recharges at midnight.
