The rupees regenerate over the course of time in the fight. If he runs out of rupees, he can't use the attack, so 'as long as he has enough rupees,' he can use this attack.
The longer the charge, the farther they go. The rupees can be charged up to be shot farther. Morshu shoots 8 red rupees that make a circle around him.
Morshu exits his shop and steps onto the battlefield.
