The Gungans are a reverent people with a pantheon of gods looking over their lives. Priests can be extremely influential in Gungan society, though some have used such authority for their own gain. Minister Rish Loo is said to have many connections to ancient mystical powers, but where his true motives lie remain uncertain.
Rish Loo used a mystical talisman to brainwash the Gungan leader Boss Lyonie to do his bidding. Under Rish Loo's spell, Lyonie began speaking against the Naboo, urging a Gungan uprising against their surface-dwelling world-mates. When Lyonie came to his senses and confronted Minister Loo, the treacherous priest stabbed the boss, gravely injuring him.
Anakin Skywalker was able to sense through the Force that something unusual was at play in Boss Lyonie's actions against the Naboo. Skywalker removed the talisman that was controlling Lyonie, and gave chase to Rish Loo, pursuing the fleeing minister into the Naboo swamps.
After Rish Loo injured Boss Lyonie, Jar Jar Binks took the boss' place thanks to his uncanny resemblance to the Gungan leader. Posing as Lyonie, Jar Jar publicly condemned Rish Loo for his actions, and turned the Gungan Grand Army away from Rish Loo's plot.
Rish Loo was in direct communication with Count Dooku, who was seeding discontent on Naboo. Rish Loo hoped to secure a position of power in the Separatist Alliance, but once Dooku was done with him, the former Jedi coldly ran through the minister with his lightsaber.