Spamming the Tavern to get you to purchase his wares.
"You can complete challenges for free gold."
"Need a vault chest for cheap? Complete some challenges for free gold!"
"Your storage looks a bit full. Complete some challenges for free gold and expand!"
"Check out your challenges- the crossed-swords icon. They grant free gold on completion!"
"You earn free gold for completing challenges. Check out the crossed-swords icon for more information."
"If you're ever running low on gold, you can complete some challenges for more."
"Need a backpack but have no gold? Try completing your challenges- they grant gold upon completion."