Kuwaq Yaku – The Forge DLC - Crafting and Using Grenades

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Once you've completed the FORGE OF DESTINY CHALLENGE TOMB and unlocked the Grenadier Skill, Lara will be able to craft and fire grenades. Equip the rifle (keyboard 3 or D-Pad Right).

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Then without aiming, hold the Alternate Fire button (Middle Mouse/R1/RB). Lara combines black powder, salvage, and fat from inventory to make a grenade.

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To use it, aim with the rifle...

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...and press Alt Fire (Middle Mouse/R1/RB).

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Boom!

P.S. If you blow up the little, blue frog sitting on the bank here, we are no longer friends. :(

[Mission Walkthrough| Kuwaq Yaku Walkthrough]