Items

Overworld
Medkit: Used to heal other players or mobs

Golden Medkit: Used to heal players or mobs past max health

Liquid Ingot: Smelts from Liquid Ore and is used to make armor

Scuba Helmet: Gives Water Breathing in water for longer than a turtle shell

Chestplate of the Drowned: Grants Haste in water

Dolphin Pants: Grants Dolphin's Grace in water

Noncombustible Boots: Protects against fire and lava damage for a limited amount of time

Nether
Fire Crystal: A throwable fireball that solidifies liquids and explodes

Unstable TNT: Looks like normal TNT but explodes when broken

End
Upgraded Pearl: An enderpearl that can be controlled

Rush Pearl: A rideable enderpearl

Pure Corruption: Used on a sword to corrupt it

Corrupted Armor: Grants speed when worn with a chance of granting slowness

Other
Ice Helmet: A helmet that can freeze attackers

Ice Boots: Boots with a high level of frost walker