WIP doodle ideas for monster cards. The idea is that in the overworld themed dungeon portals can randomly spawn, and the player can enter into a timed trial to defeat mobs / and do whatever else they want to do in the randomly generated dungeon. There are multiple themes a dungeon can have. There are mobs which are rarer than others. Mobs have a low chance to drop their monster cards. Once you have a monster card, you can then spawn that mob's eggs on your own overworld. If a mob is on an island it will stay there otherwise it will be able to roam around and potentially interact with other mob types. And you can kill your own mobs on your overworld to farm their materials, but spawning eggs can be costly, and I'll probably add a forced wait cooldown time to spawn eggs too.
So each dungeon theme has a set of monster that can spawn, each theme has a set of monster cards to collect, each theme will have its own card border art style and the monsters within it will fit the theme well. There could be super rare mobs which can spawn in any themed dungeon zone too!
Each mob would need its card art appealing look. Two frames for movement, one frame for action, one frame for taking damage.