Deep Woods, Dark Heart was the planned but ultimately unreleased thirteenth adventure for the RPGA's Mark of Heroes campaign using the 3.5-edition Dungeons & Dragons rules and set in the Eberron campaign setting. It was to be released in 2006 and was intended for 9th-level characters.
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A member of House Vadalis has gone missing, and divination has determined she has been kidnapped by the dark and mysterious Children of Winter. Can you save the girl before she is sacrificed within an unholy grove deep in the heart of the Gloaming?
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— Synopsis