Introduction

• You can use the Tome of Reveries in the theater prep room to start the Imaginarium Theater challenge. There are 8 stages in the challenge. Rewards are given according to the number of stages completed.

Stages

• The 3rd, 6th and 8th stages are Boss Stages. The other stages are ordinary stages.
  The first stage is Lv90, and the level increases gradually, to Lv95 in the final stage.

• Every phase of Imaginarium Theater specifies 6 Opening Characters. They will gain 20% Max HP, ATK and DEF bonus in the Imaginarium Theater and in the realm of Teyvat.
  Before entering Imaginarium Theater, you need to choose:
  – 6 Opening Characters. If you do not have some of them, you must choose the trial version.
  – 12 Backup Characters. One can be a Support Character from a friend. One can be a Special Invitation Character. The remaining at least 10 characters must be your own characters of the three fixed Elements specified by each phase.

• Upon entering Imaginarium Theater, your team will only consist of the 6 Opening Characters. Every character starts with 2 Vigor, and after every stage the characters participating in combat will lose 1 Vigor. One random character from the Backup Characters is chosen to join the team.
  In Imaginarium Theater, you can choose any characters in the team as your active party.

Friend Support Character

• One character chosen from your friends’ provided characters. Each player can provide up to 7 characters. Every player can only choose 1 character from 1 friend in each phase.
  You can provide any characters except the Traveler, but your friends can only choose characters of matching Elemental type and Special Invitation Characters.

Special Invitation Character

• Pick 0~4 characters from 4 fixed characters in each phase. There are no trials so if you do not own a character you cannot pick them.

Special Invitation Character

• Pick 0~4 characters from 4 fixed characters in each phase. There are no trials so if you do not own a character you cannot pick them.

Stage Rules

• Before the battle in each stage, you can spend Points choose Events from a list of randomly generated Events. You can also go into battle without choosing an Event.
  Choosing Events consumes Points. Completing battles reward Points. You can choose different difficulties for the battles and will be rewarded with different amounts of Points. Completing Extra Challenges in battle will reward extra Points. Example: Deal Electro DMG 40 times in this battle.

Points and Stars

• There is no time limit for simply clearing a stage. However, if battles are completed within limited time, “Perfect Performance” is achieved and you will gain a Star.
  Stars will not affect rewards, but will give you badges that can be displayed in your profile.

Stage Events

• There are many Events, such as:
  Companion Events – Choose a character in Backup to join your team.
  Buffs – Provide buffs to your team in combat.
  Mysteries – Could be buffs, could be bad things.

Stage Battles

• Some battles require you to defeat all enemies. Others require you to defend a Domain Monolith.
  Every stage will have some random Stage Effects, such as:
  – A period of time after the challenge begins, thunder will descend and strike your characters.
  – A period of time after the challenge begins, all party members will continuously lose small amounts of HP.

Source: HomDGCat