When Graham broke the viper enchantment on Pegasus he was given the Magic Sugar Cube in return. The cube would allow him to walk through poisonous brambles without being killed. It looks just like a regular sugar cube but had a bit of a sparkle.
Background[]
After King Graham threw the bridle on the snake in the cliffs above Kolyma, it was transformed into the winged horse Pegasus. Pegasus gave Graham a sugar cube to protect him from the poison brambles that entirely cover the island on which Dracula's castle stands. It is well known that sugar cubes are a favorite treat for all horses, which is probably why Pegasus bestowed his magic gift in this form.[1] It is said that sugar cubes are a cure for scratches.[2]
See also poison, venom, toxin and bane for some of the similarities and differences between terminology. This article is not the place to discuss pedantic online debates on terminology.