In Chapter 10 of The Lies of Locke Lamora Bug, Calo and Galdo are killed at the hands of the Gray King. This is Locke’s death offering promise:
“I promise you a death offering, brothers,” Locke whispered when he’d finished. “I promise you an offering that will make the gods themselves take notice. An offering that will make the shades of all the dukes and capas of Camorr feel like paupers. An offering in blood and gold and fire. This I swear by Aza Guilla who gathers us, and by Perelandro who sheltered us, and by the Crooked Warden who places his finger on the scale when our souls are weighed. This I swear to Chains, who kept us safe. I beg your forgiveness that I failed to do the same.