DESCRIPTION
"A monstrous, black-scaled, reptilian head pushes into the suite, its skull alone just as wide and half as tall as the doorframe itself. Horns resembling pointed, elfin ears thrust up from the sides of its head, and its eyes glimmer with cruel, malevolent purpose."
Rahadin appears briefly but memorably in the Verushka's Nightmare portion of the PC's overnight stay in Ravenloft, symbolically represented as a great dragon whose breath is meant to encumber the PCs in chains of gold. It's meant to represent how he, for years, would lure the youth of Barovia into Strahd's cluthes with promises of wealth, love, immortality... but death awaited them all.
And now your PCs probably think Rahadin is a dragon.