Summary
Very rare quality magic items inDungeons & Dragonsare meant to be handed out to characters in the third tier of play between levels 11-16. Consequently, these are some of the most powerful magic items that characters will acquire during their career as adventurers.
Of course, you could choose to hand out some of these items at earlier levels. While players will certainly love a Dungeon Master (DM) who chooses to do so, you risk trivializing many encounters by giving players access to such power so early. In other words, dispense these awesome items with caution.

10Belt Of Fire Giant Strength
Buffbarian Incoming
This version of the Belt of Giant Strengthrequires attunementand increases a character’s Strength score to 25. Seeing as character ability scores typically max out at 20, you can imagine how this belt breaks the inherent math of the game a bit.
Nonetheless, Barbarians and Fighters are likely to feel outclassed by full spellcasting classes at these levels. The sheer ridiculousness of high-level spells may have them feeling left out, and the Belt of Fire Giant Strength helps to even the playing field a bit.

9Crystal Ball
The Best Way For A Villain To Stay Informed
Ever wanted to spy on your enemies from the safety of many miles away? The Crystal Ball requires attunement and allows its user to cast the scrying spell with a DC of 17. Scrying is an incredibly useful fifth-level divination spell that lets you look in on a creature of your choice as long as they are on the same plane as you.
Of course, the target must first fail a Wisdom saving throw if you want to see what they’re up to. Thankfully, your knowledge of the target as well as your procurement of any items that have to do with them can make it so that the spell almost always works. You can also use scrying to view a specific location if you know to keep an eye on it.

8Helm Of Brilliance
It’s… Too… Beautiful!
This helmet requires attunement and is set with tens of different gems ranging from diamonds to opals and rubies. As long as the helm is set with certain gems, you gain access to benefits including resistance to fire damage, a dim-light emitter that deals 1d6 radiant damage to undead within 30 feet, and the ability to make your weapon burst with flame and deal an extra 1d6 fire on an attack.
You can also remove gems from the helm to cast the spells Daylight, Fireball, Prismatic Spray, or Wall of Fire with a DC of 18. This is the perfect item for a martial character who wants to dabble in spellcasting. Lastly, when the wearer fails a saving throw that deals fire damage, they roll a d20.

On a 1, the helm and its gems are destroyed and each creature other than you within 60 is subject to a DC 17 Dexterity saving throw. Anyone who fails this save takes fire damage equal to the remaining gems in the helmet. In other words, the chance that the helm nukes your party is a great incentive to use gems quickly.
7Ring Of Amity
Ooh, You Make Me Live Now Honey
Amity means a friendly relationship. This attunement-required ring lets you bond with one willing creature every long rest. While bonded in this way, any healing that you receive restores the same amount of hit points to the bonded creature. However, it gets much better than that.
As a reaction once per day, you can turn any attack roll the bonded creature lands into a critical hit as long as you are within 60 feet of them. Rogues and Paladins in particular are great characters to bond with as they excel at dealing tons of damage in a single hit using sneak attack and divine smite.

6Efreeti Bottle
Never Trust A Genie
This magic item doesn’t require attunement and is capable ofsummoning an efreetito your side. The efreeti are fire genies with a Challenge Rating of 11 capable of casting powerful spells including conjure elemental, wall of fire, major image, and plane shift.
They also have a fairly strong melee and ranged multiattack option. Unfortunately, the efreeti you summon has a ten percent chance of being hostile towards you when you summon it. That being said, there’s also a ten percent chance that the efreeti grants you up to three wishes. All in all, this is a great magic item for players and DMs who like to gamble.

5Eldritch Staff
Anddddd, It’s Gone
This is a +1 staff that requires attunement. It also comes with ten charges and recharges 1d6 + 4 of them at dawn. You can expend up to three charges when you make a melee attack to add an additional 1d8 lightning damage to the attack per charge spent.
Alternatively, you can use a reaction and spend three charges when you take damage to turn invisible until the start of your next turn and teleport up to 60 feet to a space you can see. Every character can use a built-in escape method, and having one available as a reaction is about as good as it gets.

4Oathbow
Murder Oath, Nice
For a long time, this was the only magic bow in the game available to characters. Thankfully, that’s no longer the case, however, this remains an incredibly powerful ranged attacker item. Once per day, you can choose a target to become your sworn enemy.
As long as you are attacking your sworn enemy with this weapon, you gain advantage on all attacks. Furthermore, you suffer no disadvantage from long range and your target can only benefit from total cover. As if all of that wasn’t good enough, the sworn enemy also takes an additional 3d6 piercing damage on every successful hit. Long story short: don’t annoy anyone wielding an Oathbow.

3Mindblasting Cap
Great For Mind Flayer Parties
This fairly unknown item from Phandelver and Below: The Shattered Obeliskrequires attunement and gives a character mind flayer-like powers. Once per day, while attuned to the cap, you can use a bonus action to fire a 60-foot cone of energy. All creatures hit by the cone must succeed on a DC 15 Intelligence saving throw or take 5d8 psychic damage and become stunned.
If a target fails the saving throw, they can save against the stunned condition again at the end of their next turn. A target who succeeds takes half damage and is not stunned. The fact that this gives you a mind blast in exchange for only a bonus action is simply ridiculous. Even mind flayers have to use an action to cast their mind blasts.

Be warned: this item can easily trivialize encounters when put in the right hands. After all, most monsters are quite poor at succeeding on Intelligence saving throws.
2Bloodshed Blade
That’s Going To Leave A Mark
Introduced in Bigby Presents: Glory of the Giants, the Bloodshed Blade takes up an attunement slot for the very worthwhile ability to completely nuke a single opponent once per day. On top of that, the weapon also adds your Constitution modifier to damage rolls made with it.
Once per day, you can roll and add your hit die to one attack roll made with this weapon. If the attack hits, you can then also spend and roll as many other hit die as you have remaining. In other words, a tenth-level Barbarian that lands an attack with this weapon could add up to 10d12 additional damage to the attack. That’s arguablya little too much damage, don’t you think?

1Staff Of Power
Beware Of Breaking Over Knee
Last but certainly not least, the Staff of Power is a well celebrated item that can only be attuned to by Warlocks, Sorcerers, and Wizards. This staff gives the wielder a +2 to damage rolls, their spell save DC, their Armor Class, and their spell attack rolls. It also has 20 charges which you can expend to cast various powerful spells.
They include wall of force, cone of cold, fireball, lightning bolt, hold monster, levitate, magic missile, and ray of enfeeblement. Finally, you may use an action to break the staff over your knee causing an apocalyptic explosion capable of dealing up to 160 force damage to creatures who fail a DC 17 Dexterity saving throw.
When this happens, the wielder of the staff has a 50/50 chance of either teleporting to another plane or taking double the damage that the staff causes with no save. Good luck with that.