IMO this would make spellcasting less useful, as it would be easier to take a dragon and claw through armies of monsters, picking up reagents as you go. You can then sell the reagents to the poor spellcasters struggling to get enough for a zombie-killing cast. It does seems like an interesting idea though. It is sort of like alchemy but the kind you take around with you and needs less ingredients. If we are heading this way, why not just change the alchemy ingredients so they are easier to make? This seems to be the main reason it is not used too widely - ingredients are rare enough not to bother with it and look for ready-made things in shops instead. Maybe decrease the weight of potions too so you can carry many around with you and be a pure alchemy-based damage dealer. Cavehippo/mwedel's idea about long term food benefits seems good too, although not related to this thread as such.