Avery Self-Adhesive Removable Labels, 1 x 1.5 Inches, White, 500 per Pack (05434)

I use a few of these: https://a.co/d/0iQPZQ7g Two of the 14 compartments for the heroes and monster groups, and one of the larger 15 compartments for the roaming monsters. Then I label the lid above each compartment with these: https://a.co/d/01IOfufg Works like a charm.