Summit Forest - Stormguard Sanctum Challenge Tomb - Part 2

Pick up more arrows if you need them and turn to face the climbing wall on the far side of the cave.

Use Survival Instinct if necessary to get a clearer view.

Use a fire arrow to light the lantern in the cave opening above the climbing wall...

...and another to burn away the pile of debris blocking the opening.

Then step out onto the jutting beam.

Jump toward the climbing wall and press Interact to latch on with your axe.

Climb to the top.

Follow the short passage to the treasure chest. Open it for 1250 XP, plus 250 salvage points and the Summit Forest Relic Map, which reveals both relic and documents in the area on your in-game map.

Follow the tunnel back to the opening overlooking the camp. To get down, either hang from the edge and drop, taking a bit of damage, which Lara will quickly regenerate; or, jump over to the jutting beam and drop from there. Use the camp if you like. Then follow the tunnel back to the main area.