With the new conversion of ingredients for the challenges there seems to be some confusion and a lot of questions so posting this to clear things up.
Many of them seem to work in loops as I have tried to list them. Any item in the lists can be exchanged for the item coming directly after it.
Regular Item Conversions
Goblets->Shards->Scraps->Scrolls->Goblets
Scripts->Scorps->Charms->Wings->Scripts
Charms->Fragments->Scripts (scripts do not become charms however)
Coins->Arrowheads->Talismans->Coins
Epic Item Conversions
Scrolls->Goblets->Scorpions->Scraps->Scrolls
Fragments->Scripts->Shards->Charms->Fragments
Charms or Scraps->Wings->Scripts or Goblets
I know its fairly confusing. So as an example in normal items Goblets can be traded in for shards but not scraps unless of course you trade in goblets for shards then your shards for scraps.
All exchanges are input 20 get 10. So in the above example to turn your goblets into scraps you would need to change 40 into 20 shards and then those 20 shards into 10 scraps.
Epic exchanges also require 1 epic dungeon token fragment