Everyone chooses their character. Doesn't matter which one you choose.
You can print these out on card stock and cut them, and put them into circular stand.
When you roll to see which enemy deck you'll be facing, you can roll one of these.
If you roll 6 (or the empty side) you face the mono colored deck of the terrain you're traveling to. Otherwise this will tell you the second color of the multicolor deck you'll be facing. So if you're on a forest and you roll 5 or 6 you'll face the mono green Enchantress.
This D-6 texture image can be used in tabletop simulator: