Combine them with one of the 3 Improvement Stones and you get a portal. With this portal you can access a short dungeon in which you will fight “Shadow I”. After this battle, it will give you 1 awesome equip and the portal to the next dungeon. This goes on till you defeat “Shadow IV”. Every Shadow gives you one more equip. You can only have access to Trial Portals if your level is just Trial Level +3.