Overall, Royal Guardian gear is arguably the best set in the mod. The Royal Guardian Sword does 750 attack damage, has 9000 durability and has extended reach. Royal Guardian armor has a multitude of enchantments, ranging from Projectile/Fire/Blast/Protection X to Feather Falling/slow fall and Respiration. It also has the following statistics:
Helmet: 8 defense (4 armor bars)
Chestplate: 14 defense (7 armor bars)
Leggings: 12 defense (6 armor bars)
Boots: 8 defense (4 armor bars)
Royal Guardian gear is primarily obtained by defeating The King, which spawns on top of The Tree of Goodness in the Utopia Dimension. However, it can also be obtained by defeating The Queen (which spawns on top of The Queen Tree in the Utopia Dimension), or by completing the 6 tier challenge dungeon in the Danger Dimension.