The Eye of the Hydra

A dark, floating eye from a hydra follows you wherever you go...
The Eye of the Hydra grants a +1 to your Spell Save DC and augments your eldritch blast with thunder damage. This augmentation adds an additional 1d4 thunder damage to your eldritch blast.
As a bonus action you may channel the regenerative power of hydras to restore your body. You regain a number of hit points equal to 2d10 + your Constitution modifier. You may use this feature a number of times equal to your proficiency bonus. You regain charges on a short rest.
Your never so distant companion keeps a watchful eye for you wherever you go. While you are awake you have expertise in perception and have advantage on perception checks that require sight. The Hydra's Eye may make perception checks while you are asleep that require sight. The Hydra's Eye has darkvision out to 60 feet. 
Spectral Hydra Heads. A number of spectral hydra heads equal to your proficiency bonus sprout from your shoulders increasing your reach to 10 feet. Only you and creatures with truesight can see the heads. The following features consume one head when used. When a head is expended, its appearance becomes wispy and gaseous, but its glowing eyes remain. You regain all expended heads when you finish a long rest. In addition, you can use a bonus action to beseech your patron to restore two of your expended heads. Once you use this ability, you can’t use it again until you finish a long rest.

• Once per turn, you can expend one head when you hit a creature with an attack to cause that creature to take extra psychic damage equal to 1d10 + your proficiency bonus.
• When you fail a death saving throw, you can expend one head to succeed instead.
• Once per turn, you can expend one head to take a reaction even if you’ve already used your reaction. You can’t use this benefit on the same turn that you take your normal reaction.
• When you fail a saving throw against being charmed, frightened, or put to sleep by magic, you can expend one head to reroll the saving throw. If you do so, you must use the new roll.