all items inside material tab is safe to edit. i usually edited to 2m each material, more than 10m for rune stone, feather, and mana essence haha.
have you try to use 'WARP 1.1.1.1' and remove the game data? just to make sure...
and if you are new and not sure which item is safe, you better to hack 1 type of item at a time. because if you hack more than 1, when you got banned you will be confused which one trigger the ban. after you hack the item then use it and wait for 30-60 mins before you reopen the game. if you don't get banned it should be safe. anyway try to use 200 tech book bundles haha, don't be greedy and consumed too much item at one time.