Vexing Puzzlebox

Whenever you roll one or more dice, put a
number of charge counters on Vexing Puzzlebox
equal to the result.
{t}: Add one mana of any color. Roll a d20.
{t}, Remove 100 charge counters from Vexing Puzzlebox: Search your library for an artifact
card, put that card onto the battlefield, then
shuffle.