I have yet to find them all. Heck I didn't expect another series out so quickly after the first. But I grabbed two of the boxes bc the others were partially or fully opened so I couldn't guarantee the right codes, and that's the whole point! This is going to be a post in progress until I can fill them all in. Feel free to post in comments if you know the codes and what they are. =)
Minecraft Series 6: End Stone Codes
C- Steve with shield (awesome orange and green creeper face paint scheme)
K- Nether Portal Pigman* only in one packs
*only in one packs
The options are magma cubes (3 stack), laser-firing guardian*, Alex with shield, blacksmith villager*, baby horse*, Steve with shield, pig in minecraft, spectral damage zombie, shulker, potion-drinking witch, exploding creeper.