Something I just recently found out about despite having played for so long; if you have certain rings equipped in a certain order, you get passive bonuses.
Angel Set(+2 Luck): Solar Rays, Healing Halo, Hunter's Bow, Wish
Athlete Set (Debuff Immunity): Bump, Turtle, Fitness, Taunt
Chef Set (+70 Dodge): Knife Sharpen, Meat, Pot Lid, Hack
Demon Set (+2Hp Regen): Fire Rain, Teflon Spray, Iron Will, Scaredy Cat
Medic Set (+48 Speed): Adrenaline, Bandage, Defibrillate, Diagnose
Ninja Set (+30 Accuracy, +30 Dodge): Divinity, Ghost, Mantis, Shuriken
Pirate Set (+10% Persistent Armor): Quicksand, Keen Aye, Shark Attack, Slash
Prankster Set ( +300 Max Health): Fleet Feet, Gumshoe, Heavy Water Balloon, Hot Foot
Space Trooper Set (+70 Accuracy): Guns, Duct Tape, Improbability Sphere, My Density
Shaman (+1SP Regen): Dervish, Hornet's Nest, Rock Armor, Coyote Spirit