This staff has 3 charges and regains 1d3 expended charges daily at dawn.
The staff can be wielded as a magic Quarterstaff. On a hit, it deals damage as a normal Quarterstaff, and you can expend 1 charge to deal an extra 2d10 Necrotic damage to the target and force it to make a DC 15 Constitution saving throw. On a failed save, the target has Disadvantage for 1 hour on any ability check or saving throw that uses Strength or Constitution.
RollQuest summary 3 charges; regains 1d3 at dawn. On hit, expend 1 charge: +2d10 Necrotic; DC 15 CON save or Disadvantage on STR/CON checks and saves for 1 hour.
RollQuest ships the D&D 2024 SRD as a content pack, on a 5e character sheet that does the maths - roll from the sheet and let the numbers work themselves out. Free to start.