It came to my mind that there’s very little information about world of Tyria in the game (or is it just me?
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Therefore my suggestion would be to add scrolls, books, artefacts, tablets, wall writings and such across Tyria. Finding each would give some small reward but also tell something about world – some fragments of history, bestiary, maybe diary of haunted mind of a warlock of the past. And a long term achievement(s) to get
It would be really cool to enter a cave or ruins and gain knowledge of what we visit was many years ago.
It’s a lot of work but I think that it would make travelling a lot more compelling to players