The Arcane Guardian is undoubtedly one of the toughest bosses from the mod. In light of that, the
Compendium recommends being very well prepared before going up against it in battle.
Arcane Compendium Entry
A mage of ancient times, the Arcane Guardian has access to a wide range of spells. From attacks to buffs to debuffs, prepare for a magical duel that will test your counterspell knowledge. Protected by a powerful sigil, the Arcane Guardian has as many tricks against melee opponents as it does for ranged attackers.
Recommended level: 45
According to the Compendium, the Arcane Guardian must be summoned using a structure called the Shrine
of Knowledge. It is constructed by placing 2 pillars of bookshelves three blocks high one block apart, and placing a lectern with an Arcane Compendium in between.
Then, place a ring of Iron Inlay directly in front of it, and throw in an arcane essence. Then, the battle will begin. :)
The primary attack that the Arcane Guardian uses is a version of an arcane projectile spell that, without
magic resistant armor, does 8 damage, so take precautions. It will also heal itself after taking damage, and is very, very fast. When confronted with physical attack, it will flip the sigil at its back forward, using it as a kind of shield, knocking back physical attacks, and may also teleport and approach from behind. It has 115 health, which sounds small until you realize that without finding a way to prevent it from healing, it will just keep regenerating its health back from whatever damage you did to it.
Like all other bosses, the Arcane Guardian drops an Infinity Orb (green), with a rare chance of either its own element, or an item called the Arcane Spellbook, which has the Soulbound enchantment, and will soon increase the effectivness of all spells cast from it.
The Arcane Guardian appears to be a lich. This would make sense, as liches are depicted as masters of magic