This staff can be wielded as a magic quarterstaff that grants a +2 bonus to attack and damage rolls made with it. While you hold it, you gain a +2 bonus to spell attack rolls.

Wraith Pact: you are able to shunt the staff away into extra dimensional space (Refer to Pact of the Blade) Specific only to this weapon. 

Eldritch empowerment: (1 Charges) While attuned to this staff you may fire one additional beam of eldritch blast when casting that cantrip. Duration: 1 hour

The staff has 11 charges for the following properties. It regains 1d6 + 2 expended charges daily at dawn. If you expend the last charge, roll a d20. On a 20, the staff regains all charges. On a 1 you must roll a Wisdom saving throw: DC 17. On success nothing happens, on a failure (REFER TO DM) 

Wraith form: (3 charges) You Shift into a gaseous wraith form with a flying speed equal to your half of your walking speed. Your have resistance to all non magical physical attacks. You cannot expend charges on spells while in the Wraith form. Only Cantrips and Eldritch abilities are able to be used in this form. 

Spells. While holding the staff, you can use an action to expend some of its charges to cast one of the following spells from it, using your spell save DC and spellcasting ability: Identify (3 charges), dispel magic (3 charges), fireball (6th-level version, 7 charges), flaming sphere (4 charges), invisibility ( 3 charges), knock (3 charges), lightning bolt (4th-level version, 6 charges), plane shift (8 charges), telekinesis (2 charges), wall of fire (4 charges), or Vampiric touch (6th level 5 charges).

You can also use an action to cast one of the following spells from the staff without using any charges: detect magic, enlarge/reduce, light, mage hand, or Pass without Trace. 

Spell Absorption. 2/day While holding the staff, you have advantage on saving throws against spells. In addition, you can use your reaction when another creature casts a spell that targets only you. If you do, the staff absorbs the magic of the spell, canceling its effect and gaining a number of charges equal to the absorbed spell's level. However, if doing so brings the staff's total number of charges above 11, the staff explodes as if you activated its wrathful strike (see below).

Wrathful Strike. (Willing) You can use an action to break the staff over your knee or against a solid surface, performing a retributive strike. The staff is destroyed and releases its remaining magic in an explosion that expands to fill a 30-foot-radius sphere centered on it.

Upon its destruction, You have a 50 percent chance to instantly travel to the Wraiths plane of existence forever shunting your soul into the staff. If you fail to avoid the effect, you take force damage equal to 16 × the number of charges in the staff. Every other creature in the area must make a DC 17 Dexterity saving throw. On a failed save, a creature takes an amount of damage based on how far away it is from the point of origin, as shown in the following table. On a successful save, a creature takes half as much damage.

Notes: Bonus: Magic, Bonus: Spell Attacks, Advantage: Saving Throws, Sorcerer, Warlock, or Wizard, Damage, Control, Detection, Combat, Deception, Warding