The Ruin Serpent is one of the intriguing Field Bosses in Genshin Impact, known for its mechanical nature and unique combat mechanics. Here's an in-depth look.
Image via HoYoverse.
The Basics
Location: Liyue Region: Specifically, the Ruin Serpent can be found near the Luhua Pool, which is south of the city of Liyue, in an area that's rich in ancient ruins.
Appearance: The Ruin Serpent manifests as a large, serpentine machine with multiple segments, each capable of independent movement and attacks. Its body is covered in metallic plates, with glowing blue or green accents, giving it a futuristic, ancient ruin vibe.
Combat Mechanics
•Phases: The fight with the Ruin Serpent involves dealing with its segmented body:
•Initial Phase: It starts with a protective shield that must be broken to damage its body directly.
•Segmented Attacks: After breaking its shield, each segment can attack independently, requiring players to manage multiple threats.
•Critical Phase: When sufficiently damaged, it will attempt to regenerate or repair itself, which is a window for players to deal critical damage.
•Laser Beam: Fires a powerful laser from its head segment, sweeping across the battlefield.
•Projectile Barrage: Launches a series of missiles from its body segments.
•Electro Shock: Emits an Electro field or shockwaves that can paralyze or damage players.
•Slam Attack: The body segments can slam down, creating shockwaves on impact.
•Regeneration Attempt: When critically damaged, it might try to repair itself, which can be interrupted for bonus damage.
Strategy 
•Elemental Weakness: The Ruin Serpent is primarily resistant to Electro but can be vulnerable to reactions like Overload (Pyro + Electro) or Electro-Charged (Hydro + Electro) if players can manage the reactions effectively.
Avoiding Damage:
•Utilize characters with high mobility or crowd control like Venti or Jean to avoid the multi-segment attacks.
•Characters with shields, especially Zhongli, can mitigate the damage from its laser and shock attacks.
DPS Focus:
•When its shield is down, focus on the main body or critical segments. Characters like Eula or Razor can deal significant single-target damage.
Elemental Reactions:
•Triggering reactions can help in managing the boss's multiple threats, especially Overload, which can disrupt its attacks by knocking back its segments.
•Healing and Shielding: Given its high damage output, having a strong healer like Bennett or Kokomi can be beneficial.
Team Composition
•DPS: Characters like Diluc or Keqing can exploit reactions or deal high physical damage.
•Supports: Characters like Fischl for consistent Electro or Xingqiu for Hydro can set up reactions.
•Healer: Diona for healing with Cryo resonance or Barbara for Hydro application alongside healing.
•Utility: Zhongli for shields, or Sucrose for Elemental Mastery and crowd control.
Rewards
•Defeating the Ruin Serpent grants:
•Primogems
•Hero's Wit
•Mystic Enhancement Ore
•Talent materials like "Teachings of Resistance" or higher tiers for character ascensions.
Tips: 
•Segment Focus: Initially, focus on one segment to break its shield. Once broken, switch focus to maximize damage.
•Elemental Mastery: Characters with high Elemental Mastery can benefit from the reactions, especially Overload.
•Dodge Timing: Learn the timing of its laser and shock attacks to avoid significant damage. The Ruin Serpent's moves are telegraphed, allowing for strategic dodging.
•Interrupting Regeneration: When it attempts to regenerate, use your highest damage abilities to interrupt it, as this can deal bonus damage and prevent it from healing.
Additional Strategy Details
•Environmental Awareness: The battlefield around Luhua Pool provides opportunities for strategic positioning. Use the terrain to your advantage, dodging between structures or using them for brief cover.
•Team Rotation: Efficient character switching can help manage the Ruin Serpent's multiple attack patterns. Have a plan for when to heal, shield, or switch to high DPS.
•Managing Reactions: Since the Ruin Serpent is resistant to Electro, using Hydro to trigger Electro-Charged might be less effective than using Pyro for Overload, which can disrupt its segments.
The Ruin Serpent offers a unique challenge due to its segmented body and the need for players to adapt to its changing attack patterns, making it a memorable and engaging fight in Genshin Impact.
