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From Pathfinder Secrets of Magic, which isn't enabled.

Rough Terrain Stance

FEAT 6
Activity 1 action
Archetype Geomancer
Prerequisites Geomancer Dedication; expert in Nature

Requirements You gained a terrain attunement benefit this turn. You need to meet this requirement only to enter the stance, not to remain in it.

You enter a stance that makes it difficult to move around you. Each square adjacent to you becomes difficult terrain that matches the terrain attunement you gained (rime forms in an arctic terrain, momentary undergrowth shoots up in a forest terrain, and so on). You ignore this difficult terrain.

This stance ends if you move into a different type of terrain.

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