The Diablo 4 Brought to Heel side quest asks you to collect a red mushroom for Lumir, an NPC you find once you've explored the south and ventured into Hawezar. This is a fairly high-level area so you won't normally come here until later. Even if you decide to farm renown by uncovering every portion of the map, you won't be able to see any side quests until you reach the appropriate level.
If you're still low-level, knowing the best XP farm spots could help you out—you'll also want to get your mount unlocked as soon as possible to make getting around a little easier. For everyone else, here's how to find the red mushroom so you can complete the Diablo 4 Brought to Heel quest.
