Think of tokens in three classes:
1. Consumables - Scrolls, ammunitions, potions and the like. These are surrendered at the time of use, where ever you are (training or dungeon).
2. Creative use of tokens. If you ask the DM if you can use a token in a specific way that might "break it or use it up", or the DM indicates (as in the Harpy) you need to sacrifice items, you may have to turn those in. The DM will tell you, ahead of time, that you will loose the token, and you always will have a choice of not surrendering the token in exchange for the effect. [Player: DM, can I use my throwing dagger against the acid monster? DM: Yes you can, but if you do and successfully hit, it will destroy your throwing dagger and you will have to turn it in...]
3. Acts of nature, monster, or Jeff Martin. The module may be written in such a way that it might "destroy deactivate" certain items. For example, sonic blasts destroy crystal or glass vials (no potions), water destroys parchment (no scrolls), rust monster eats weapons and armor (nothing but leather survives), magical forces steal your Iuon stones, or you just plain wake up in a jail cell with all your equipment stacked neatly on the other side of the room and bars... All these are SPECULATIVE possibilities that could happen. In that case, however, you would not be asked to turn in tokens, you would simply not be able to use them for the rest of the room or adventure. It also would not be a whim of the DM that something like that would happen, it would be written into the module as a challenge for all parties to face, so no one would receive unfair treatment.
So to summarize, TD reserves the right (as part of the adventure) to prevent you from using a particular token [please trust we would use this very sparingly, we do not want to, as a routine activity, keep people from using tokens]. We reserve the right to barter with you during the game for uses of a token outside of the norm, that might include asking you to surrender the short sword you repeatedly stick in the lava pool to scoop out bits of lava. TD will not request you surrender any perminant token on a whim, nor will you ever be placed in a situation where you do not have a choice in the matter.
Fair enough?
Dave
You should know better than to pick up a duck in a dungeon....