Waters of the Styx

The vial of water from the river styx is black and hung on a thin mithril chain. It pulses with energy of spirits consumed by the water, which whisper and occasionally flash inside the small glass vial.
If you try to attune this item or discern its nature without being a warlock, you must make a DC 12 Wisdom saving throw or take 1d12 points of psychic damage, unless you are using the spell Identify.
While you are attuned to this item, you gain the following benefits:
* Your Eldritch Blast gains an additional +2 to attack and damage rolls, and their range is doubled.
* When you score a critical hit with Eldritch Blast, you gain temporary hit points equal to the damage done, and you must roll a d100 on the wild magic table, as if you were a wild magic sorcerer.
* The Pendant has six charges, and regains 1d6 charges every time you are reduced to 0 hit points. If you have no remaining spell slots, you can expend one charge to try and cast a spell. Roll a d20, and if you roll a 5 or lower, it instead casts a random spell instead. If the spell requires a target, you may designate a new target or use the target of the original spell. When this effect triggers, you regain 1 warlock spell slot. 
* You can also choose to expend 2 charges in order to regain all expended warlock spell slots, and cast a random spell at a random target.