Etheria

"You're trapped in my world now."

Etheria is a Hardmode post-Golem boss fought in anywhere at nighttime.

Spawn
Etheria, like most other bosses, does not spawn on her own and requires the player to summon her with the Emblem of Etheria during nighttime, or any time in the Etherial dimension.

Behavior
Etheria will float mid-air rapidly, dealing high-contact damage. As Etheria does this, it will barrage the player with a variety of attacks.

Attacks

 * Rapidly moves above the player.
 * Summons a spinning Etherial Tear.
 * Teleports often randomly, creating Etherial Pulses in a circular form.
 * Shoots an Etherial Waves that goes on a spiral direction.
 * Shoots multiples of Etherial Wave.
 * Shoots two Etherial Waves.
 * Etheria's mouth will open wider and her pupils dilate as 25% of her maximum health is depleted, giving her a more menacing look.

In Expert Mode

 * Her health and damage are increased.

In Etherial Dimension
After summoning her in the dimension, she retains her magical abilities but has new moves and her true form.

Behavior

 * Summons a shadow version of herself.
 * At 40% of her life, Etheria and the shadow version will turn into red and their mouth is wider.
 * 3 mirror images of the Etheria slowly appear based on the low life.

In Expert Mode

 * Her health and damage are increased.
 * Her projectile damage is increased
 * 3 mirrors appear more often.
 * Summons more Etherial Pulses that goes on each spiral together.

Aftermath

 * Once defeated for the first time, the status message "You're trapped in my world now." displays, indicated that the player is being stuck in a dimension known as the Etherial Dimension, causing the world takes on a muted cyan color. The player can only get out if Etheria is fought again.
 * Once defeated for the first time, the status message "Bysmal Venins burst through the world" displays, indicating that the Bysmal generated in the Etheria Dimension.
 * Once defeated for the second time will result in leaving the dimension.