Jack's Channeling Die

A 20-sided die made of silver and with amber edges. The sides do not contain any numbers, instead, they contain small spots of a metal-like liquid. Depending on who has attuned to the die, the liquid on the sides will shape itself into different numbers. 
Once every long rest, whenever a player who has attuned to the die makes a roll with a d20, they can choose to channel this die. By doing so, the outcome of their roll will be replaced by the number displayed on the side of this die, unless they rolled higher. The number on the side of Jack's channeling die is equal to the number of skills that the attuned player is at least half proficient with. If the roll that the player chooses to use this die for is associated with a certain skill, any subsequent roll associated with this skill will result in automatic failure. If the roll is associated with a general stat, the player will have a disadvantage with any rolls associated with that stat (including its skills).