Here's a detailed guide based on typical gameplay patterns for the quest "An Impromptu Change of Plan" from Genshin Impact. Remember, this guide reflects the general gameplay as of this writing. If there have been recent changes or updates to Genshin Impact specifics like rewards or exact quest mechanics might differ.
Unlocking the Quest 
1.Complete the Preceding Quest: Ensure you've finished the first part of Chapter 1: Act 1, likely something like "The Outlander Who Caught the Wind" if it extends into Liyue's storyline or another introductory quest to Liyue.
2.Adventure Rank: You might need to be at or above a certain Adventure Rank, which could be around AR 18-20 or higher depending on when this quest was set in the progression.
3.Travel to Liyue: If not already done, progress through the story until you reach Liyue, where the quest will likely trigger.
Quest Walkthrough
1.Start the Quest: This might begin with an interaction with an NPC, possibly Keqing, or another key figure in Liyue Harbor, indicating a shift in plans or an urgent matter.
2.Exploration or Investigation: You might be tasked with investigating some anomaly or event around Liyue, which could involve:
3.Monoliths or Ruins: Exploring ancient structures or solving puzzles related to Liyue's Geo element or its history.
4.Meet New Characters: Engage with characters like Zhongli, Ningguang, or others who provide more context or quests.
Unexpected Event: Here, something unexpected happens:
5.Combat: Engage with enemies like Fatui agents, treasure hoarders, or perhaps even a new type of monster or boss.
6.Stealth or Diplomacy: There might be scenarios where avoiding combat through stealth or negotiation plays a role.
Adapt to the Situation: This could involve:
7.A Change in Objectives: You might need to quickly switch from your original mission to address this new development, like protecting an artifact, chasing after someone, or preventing a disaster.
8.Use of Elemental Skills: Leveraging your characters' abilities to overcome obstacles or enemies in creative ways.
9.Climax: This could be a significant battle or a moment where you must make a key decision affecting the storyline.
10.Conclusion: Wrap up with dialogues revealing more about Liyue's political or mystical situation, possibly with a cutscene.
Quest Rewards
Upon completion, you can expect:
•Adventure Experience: A good amount to increase your Adventure Rank.
•Primogems: Essential for wishing for new characters or weapons.
•Mora: For general use in enhancing characters and gear.
•Character Experience Materials: To level up your party members.
•Artifacts: Possibly some unique or high-quality artifacts fitting for the early to mid-game.
•New Unlockables: This might include access to new areas, features, or the continuation of the Archon Quest line.
Quest Tips 
•Follow the Story: NPC Dialogues: Pay close attention to what NPCs say. They might give hints about what to do next or how to approach certain challenges.
•Quick Adaptation: Since the quest involves an "impromptu change," be ready to shift your strategy. If you're expecting a puzzle but suddenly face combat, switch your team composition if necessary.
•Use the Environment: Geo Constructs: If you're dealing with Geo-related puzzles or enemies, remember that Geo structures can often be used to your advantage, like creating barriers or platforms.
•Keep an Eye on Quest Objectives: Sometimes, the game might give you a new objective on the fly. Make sure to check your quest log frequently so you don't miss any changes or new directions.
•Save Often: Although Genshin Impact auto-saves, if you're about to do something risky or enter a new phase of the quest, consider using a waypoint to save manually or ensure your progress is safe.
•Co-op Mode: If you find the combat or puzzles too challenging, consider bringing in friends via co-op mode. Some puzzles or fights can be easier or more fun with others.
