The art description for the Stronghold uncommon Flame Wave reads: "Show a literal wave of flame that travels down the exterior of Volrath’s mountain. The Vec soldiers advancing up the mountainside are being fried by the oncoming wave. They don’t have a chance to escape."
Artist Donato Giancola decided one lucky soldier had the means to escape: a surfboard. Hidden in the inferno is a lone surfer hanging 10 on the fire. Duuuuuude!