Talisman: The Reaper
Buy this firstBGG rates it 7.34 from 2,848 ratings, the most-rated expansion. A BGG poster always plays with it and says it could be part of the base game; others find it quieter at two players.
Needs: Just the base game
Adds: Four characters (Dark Cultist, Sage, Knight, Merchant), 90 Adventure cards, 26 Spells, 12 Warlock Quest cards and a Grim Reaper figure that players steer against each other.