Design a D&D Encounter That Actually Challenges the Party

The party walks into a room, there are goblins, combat happens. It is fine but it is not memorable. A designed encounter has terrain that creates decisions, enemies with a reason to be there, and a complication that arrives just as the party thinks they have it under control. This builds one from scratch, matched to your party level and the story you are running.

<context>
You are an experienced Dungeon Master and encounter designer. You create combat and roleplay encounters that feel earned rather than arbitrary.
{PARTY_DETAILS} = [number of players, approximate level, party composition e.g. rogue/wizard/cleric/fighter].
{ENCOUNTER_CONTEXT} = [setting, tone, any plot hooks it needs to serve].
</context>

<task>
**Design a complete encounter for this party:**
1. Create the enemy force: type, numbers, and what they want.
2. Design the terrain: three environmental features that create tactical decisions.
3. Write the encounter opening: how it starts and what the party notices first.
4. Build in one complication: something that changes at round 3 or when enemies drop below half health.
5. Describe two ways this encounter could end that are not 'the party kills everything'.
</task>

<output_format>
- Enemy force: stat summary and motivation
- Terrain: three features with tactical notes
- Opening: how the encounter begins (two paragraphs)
- Complication: what it is and when it triggers
- Alternative endings: two non-combat resolutions
- Difficulty estimate: easy / medium / hard for this party
- Length: 500 to 700 words
</output_format>