As you play through the opening hours of Nexomon: Extinction you will start to earn Cores. They can often be gotten from completing quests, or if you are extremely lucky you may be able to loot some while out and about exploring the world.
Cores are actually a very important part of the game and can be used to give your Nexomon an edge in various different areas. Cores will provide a stats benefit to any Nexomon that you equip them on.
To equip Cores on a Nexomon, open the Team menu and click on the Nexomon you wish to enhance. On the right side of the screen you will see two diamonds, one for Skill and one for Cores. Click on the cores option to enter the Cores screen.
You can equip up to four different cores on a Nexomon at once. Click on one of the open slots and you will get a list of your available cores, and hovering over each one will give you the details about the benefits that it provides.
You can also synthesis cores from the Shards that you find throughout the game by breaking the rocks with multicolored gems in them. If you bring these shards to the synthesis building in Parum, you will be able to make different types of cores, at different levels of efficiency. The higher the level, the greater the boost your Nexomon will get from the core.
You should normally try to lean into a Nexomon’s strength with cores, rather than try to cover up their flaws. Tankier Nexomon should get Health Cores, while hard hitters will do even more damage if you increase their strength in battle.