Amulet of Tiamat

Wondrous item, legendary (requires attunement)
This gold amulet is adorned with the heads of five chromatic dragons, each one's eyes replaced with gems of the corresponding colors.
While you wear the amulet, you gain the following benefits:

You can speak, read, write, and understand Draconic.

You gain Darkvision with a range of 60ft. If you already have Darkvision, its range is increased by 60ft.

You can sense if a Dragon is within a mile radius of you, though you can't tell the exact location or direction

When a chromatic dragon dies within 1 mile of the amulet, its soul becomes trapped in the amulet, causing the eyes of the corresponding type on the amulet to glow. Once a dragon's soul has been trapped in the amulet, it cannot trap another soul of the same dragon type without first releasing the previous one. For example, the amulet cannot absorb a red dragon soul if it already has the soul of another red dragon already inside of it without removing the former soul. While a dragon's soul is contained in the amulet it, it cannot be resurrected. The amulet has a number of charges equal to twice the number of souls trapped inside it. The amulet regains 1d10 charges daily at dawn.
Some of the amulet's features require creatures to make a saving throw to resist the feature's effects. The saving throw DC is 10, and increases by 2 for every dragon soul trapped in the amulet.
When the amulet has the souls of 3 or more dragons trapped in it, you gain the ability to spend 2 charges as an action to sprout draconic wings from your back for 1 hour. With these wings, you have a flying speed equal to your walking speed.
When the amulet has the souls of 4 or more dragons trapped in it, the range of the amulet's Breath Attack features is doubled. Additionally, you can spend charges of the amulet as a bonus action.
When the amulet has the souls of 5 or more dragons trapped in it, you have draconic wings that sprout from your back and you have a flying speed equal to your walking speed. You no longer need to activate it to gain these wings. 
The amulet gains these additional benefits for every type of dragon soul trapped inside of it:

Black
The eyes of the black dragon head of the amulet are made of a jet black gem. When a black dragon's soul is trapped in the amulet, the gems emit a faint glow and a green-ish fluid can be seen swirling inside them, and you gain the following benfits while wearing the amulet:

You gain a swim speed equal to your walking speed.

You gain resistance to acid damage.

You can spend 1 charge as an action to gain immunity to acid damage for 1 minute.

Breath Attack - You can spend 2 charges as an action to exhale a jet of acid in a 30ft line that is 5ft wide. Each creature in that line must make a Dexterity saving throw, taking 6d8 acid damage on a failed save, or half on a successful save.

Blue
The eyes of the blue dragon head of the amulet are made of deep blue saphires. When a blue dragon's soul is trapped in the amulet, the gems emit a faint blue glow and lightning can be seen crackling inside them, and you gain the following benfits while wearing the amulet:

You gain resistance to acid damage.

You can spend 1 charge as an action to gain immunity to lightning damage for 1 minute.

You can spend 2 charges as an aciton to gain a burrow speed equal to half your walking speed for 1 minute

Breath Attack - You can spend 2 charges as an action to exhale a bolt of lightning in a 30ft line that is 5ft wide. Each creature in that line must make a Dexterity saving throw, taking 4d12 lightning damage on a failed save, or half on a successful save.

Green
The eyes of the green dragon head of the amulet are made of forest green emeralds. When a green dragon's soul is trapped in the amulet, the gems emit a faint glow and a green fog can be seen billowing inside them, and you gain the following benfits while wearing the amulet:

You gain a swim speed equal to your walking speed.

You gain resistance poison damage.

You can spend 1 charge as an action to gain immunity to poison damage for 1 minute.

Breath Attack - You can spend 2 charges as an action exhale caustic gas in a 15ft cone. Each creature in that cone must make a Constitution saving throw, taking 6d8 poison damage on a failed save, or half on a successful save.

Red
The eyes of the red dragon head of the amulet are made of crimson rubies. When a red dragon's soul is trapped in the amulet, the gems emit a faint glow and a flickering flame can be seen inside them, and you gain the following benfits while wearing the amulet:

You gain a climbing speed equal to your walking speed.

You gain resistance to fire damage.

You can spend 1 charge as an action to gain immunity to fire damage for 1 minute.

Breath Attack - You can spend 2 charges as an action to exhale a jet of flame in a 15ft cone. Each creature in that cone must make Dexterity saving throw, taking 8d6 fire damage on a fialed save, or half as much on a successful save.

White
The eyes of the white dragon head of the amulet are made of cloudy diamonds. When a white dragon's soul is trapped in the amulet, the gems emit a faint white glow and a miniature blizzard can be seen swirling inside them, and you gain the following benfits while wearing the amulet:

You gain a climbing speed equal to your walking speed.

You gain resistance to cold damage.

You can spend 1 charge as an action to gain immunity to cold damage for 1 minute.

Breath Attack - You can spend 2 charges as an action to exhale a blast of ice and wind in a 15ft cone. Each creature in the cone must make Constitution saving throw, taking 5d10 on a failed save, or half on a successful save.