Myr nods, and detaches a sturdy and complicated looking brass signal lantern from his backpack, of the kind used on rivers and the coast. A minute or so's practiced work with a flint and steel kindles a soft light, which the parabolic mirror reflects into a fierce strong unflattering spotlight onto the suspect wall.

Does anyone know how to find such things? He asks carefully, making no move to study the wall himself. Or should I try to open it using the same lock-picking technique as upstairs?

He keeps looking around, rather than at the wall, keeping his nightvision intact and his focus on the surroundings

Spoiler
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spot (1d20+10)[18]
listen (1d20-1)[18]
Myr's aura gives +5 to dex and initivative checks