If you already have a Crown and teleport inside the Crown Vault to remove it or pick another one, the Crown Pedestal will be guarded by two Vault Statues. The third Vault will have four Vault Statues. Each Vault Statue will spawn a Crown Guardian.
Touching the Crown Pedestal will awaken the statues and before you leave, you will have to defeat the Crown Guardians. Attacking the guarding statues before reaching for the Crown will cause the Crown to disappear, which means you won't be able to get a new Crown or return the current one in this Crown Vault, even if you defeat the Crown Guardians.
Crown Guardians have the ability to teleport, disappearing and reappearing in a swirl of green energy. The Crown Guardian fires a large green orbs which, in turn, explodes into 7 lines of 4 smaller orbs each with one additional line fired per loop. The large orb deals 12 damage and instantly spawns small ones upon hit. Each smaller orb deals 5 damage on contact. Crown Guardian's unpredictable movement and their giant projectiles are a deadly combination for anyone unprepared.
They create an explosion upon death that can destroy walls but does no damage to the player.
Crown Guardians were temporarily removed from the game in update #79. They were redesigned and re added in update #93.
The green energy that creates the Crown Guardian's body is in a much calmer state than that of a Palace Guardian.