The Roadside Stop encounter occurs after accepting the quest Unintended Consequences. The Warden must have completed the Second Sequence during the Summoning Sciences quest at the Circle Tower before the quest is available.
Notable items EditDeathroot
A harmless enough plant on its own, deathroot's thick leaves contain an extract that the Chasind have used to induce hallucinations for centuries. Sufficiently concentrated, it can be made into a deadly poison.