The Abyss Helmet has 2 abilities:
Innate: Breathe underwater
Offensive: press R to shoot lightning at whatever the crosshair is on
Infernal Armor has 2 abilities:
Innate, Invulnerable to fire and lava
Offensive, Create an explosion around you with C
The Gravity Greaves have 3 abilities/effects:
The armour negates 90% of all damage taken to the player.
Increases free falling speed when holding Shift (As of the technic verson 1.0.1.3, offensive abilties need to be on to use this ability.)
Offensive, Slow and repel approaching mobs within a 5 block radius while holding Shift.
he Hurricane Boots have 2 abilities:
Innate: Immunity to fall damage while not sprinting.
Movement: Quickly ascend by holding Jump, always sprint while on the ground