Briber's Purse enters the battlefield with X gem counters on it.
{1}, {T}, Remove a gem counter from Briber's Purse: Target creature can't attack or block this turn.
Activating the ability targeting a creature that’s already attacking or blocking won’t remove it from combat or affect that attack or block.
If Briber’s Purse has no gem counters on it, it remains on the battlefield, although you can’t activate its last ability.