Hecate is the top choice for Sub-DPS characters that utilize coordinated attacks, as it boosts the current resonator's ATK as long as these attacks land critical hits. Additionally, its echo effect summons blades that can deal damage even when the character is not on the field, making it a valuable asset in battle.

The Nightmare Inferno Rider is a formidable attacker that excels when summoned during combat. Upon activation, its ATK increases for 15 seconds, and it can deal up to 270% damage. Furthermore, this echo can be used to traverse the overworld quickly, making it a versatile choice.

The Nightmare Crownless is a powerful echo that deals a total of 270% damage each time it is summoned. Its skill can be charged up to three times, allowing for multiple uses of the echo skill and making it a valuable asset in prolonged battles.

The Nightmare Tempest Mephis is one of the top echoes for Electro DPS characters. To maximize its potential, it's essential to determine whether your Resonator scales off Resonance Skill or Resonance Liberation. If it's the former, Tempest Mephis is the better choice. Additionally, it has access to Empyrean Anthem sonata effects, making it suitable for coordinated attack Sub-DPS characters.

The Nightmare Thundering Mephis is another top-tier echo for Electro DPS characters. Similar to Tempest Mephis, its effectiveness depends on whether your Resonator scales off Resonance Skill or Resonance Liberation. If it's the latter, Thundering Mephis is the better option.

The Reminiscence Fleurdelys is a primary echo for Gusts of Welkin and Windward Pilgrimage 4-cost configurations. It grants Aero DMG Bonus to the wearer, with an additional 10% bonus if worn by Aero Rover. This echo is also suitable for Ciaccona and is a definitive choice for Erosion DPS characters like Cartethyia, making it one of the most flexible echoes in the game.

The Nightmare Lampylumen Myriad is an excellent choice for providing passive Glacio DMG Bonus and Coordinated Attack DMG buffs. Its skill deals significant Glacio damage, but its usefulness is somewhat limited compared to Hecate, as not all resonators that utilize coordinated attacks scale off Glacio DMG Bonus.

The Capitaneus is the primary echo for characters that utilize Spectro Frazzle, such as Zani and Phoebe. It is a better option than the Nightmare: Mourning Aix, as it can provide Heavy Attack DMG unconditionally. However, it can be challenging to farm due to its 3-cost rarity.

The Nightmare Impermanence Heron is an echo that focuses on Sub-DPS characters in Havoc teams, making it less flexible than other options. Its normal variants may be more useful in non-Havoc team situations. The skill itself deals significant Havoc damage, totaling over 300%.

The Impermanence Heron is an echo that increases the Resonance Energy of the equipping character and the ATK of the next character to take the field. Its skill deals over 300% total Havoc damage, making it the best in-slot choice for any Sub-DPS character running Moonlit Clouds. The Nightmare version of this echo has a more limited Midnight Veil sonata effect, which is better suited for Havoc Sub-DPS characters.

The Fallacy of No Return is the top Rejuvenating Glow echo for the best HP-scaling supports in the game. It works exceptionally well with Shorekeeper, the best healer currently available. This echo can charge Concerto Energy rapidly by holding the echo button, allowing resonators to act while Fallacy delivers a flurry of punches.

The Sentry Construct is the best echo for characters running the Frosty Resolve sonata effect. It deals significant damage as an echo and provides bonuses without needing to be summoned, making it a valuable asset in battle.

The Nightmare Kelpie is currently only suitable as the second 4-cost echo for Cartethyia's 44111 echo configuration. Its buffs are somewhat underwhelming, as they affect both Glacio and Aero DMG Bonuses. Unfortunately, it lacks a sonata effect that benefits Glacio characters, despite buffing them.