While we don’t currently have all the specifics I want to present some ideas for overworld combat, progression, skill and weapons.
Starting with combat and particularly inplementing illuvial usage the thought is to have up to 6-8 illuvials equippable like the autobattler where you have One active illuvial roaming and fighting with you at a time.
The active illuvial will will battle beside you and be partially commandable primarily through controlling the usage of their Omega ability and potentially it might make sense to start developing generic attacks and abilities they can learn and use ex: scratch, growl fire blast, type moves that aren’t exclusive to one illuvial. In addition or instead to reduce animation work similar to genshin or wuthering waves too, the active illuvial will offer and change the abilities you can use such as a fire or inferno infusion ability when using rhamphyre to your weapon, or water shield with atlas among throwing fireballs, water blasts etc depending on how lore shapes up and determines our rangers capabilities in the illuviverse.
Finally for this part take all the synergy systems from the autobattler and apply them here so your active illuvial can bond with your character and change their element affinity and class depending on your equipped weapon, you and your illuvial can go hyper depending on what you’re fighting and also you gain bonuses based on the affinity and classes of your weapon and the several illuvials you have equipped.
That roughly sums that section up.
At the start just have one or two abilities that you can unlock and level up as you use your equipped illuvials and then with time and updates you can increase level caps and add new abilities. This would go well with multiplayer and raids for making it a full fledged rpg/mmorpg esque gameloop.
Will add weapons idea below
Feel free to comment, dislike and tear down this post to make a better one :p