Core mods improve ship capabilities, except that they don't have anything to do with defense. In particular, they don't affect the Defense stat. Defense is handled by Armor mods.

You might think you should put a Tank Core mod into a Tank-class ship, and a Fighter Core mod into a Performance-class ship, but it turns out that's probably backwards. If you're trying to get more balanced stats out of your ship, it makes more sense to pick a core mod that helps fill the gaps in your ship's capabilities. Of course, if you're looking for, say, raw speed for the racetrack, maybe you do want to stick a Fighter core into a Rocket-class ship. It might be a handful in the turns, though.

There are three categories of primary core mods. Each category is concerned with improving one aspect of ship capabilities. Each of the categories has three mod types available.



Ship performance mods

These mods improve speed and handling. Except at level I, each offers some kind of temporary improvement when you achieve a precise hit, and at higher levels each offers a feature related to boost/dodge/jump.

Emphasis On Precise hit High-level feature Sold at workshops
Fighter Speed Recharges boost gauge Reduces boost gauge usage when dodging Kirite, Vylus, Ashar
Warrior Balanced Recharges weapon energy Double-jump in mid-air Kirite, Vylus, Ashar
Champion Handling Increases weapon damage for 5 seconds Jump button holds altitude Ashar
Trying to hint without creating a spoiler: one of the campaigns is more easily completed with one of these mods. So do keep them in mind even if you choose something else for your normal activities.



Weapon energy mods

These mods increase the amount of energy available to power weapons. Each offers some kind of temporary improvement when you achieve an elemental combo. An additional feature is included with mods other than level I or maybe II, and yet another feature with mods at level IV or maybe V.

Energy increase On elemental combo Mid-level feature High-level feature Sold at workshops
Elemental Some Recharges weapon energy Target assist Stuns nearby units when at critical health Sonatus, Tundria, Necrom
Nova A little bit more Recharges boost gauge Increases damage to corrupted imps and cyclops Reflect applies lift Haven, Tundria, Necrom
Warden Most Increases weapon damage for 5 seconds Increases weapon damage near electrum vein Hacks imps on impact Necrom


Pilot ability recharge mods

These mods increase the rate at which the pilot's special ability is recharged after it's used (or is charged the first time you bring the pilot in). Each offers some kind of temporary improvement when you reflect an attack using the active shields. Each has a helpful effect on nearby allied units. Additional features may be included with mods at higher levels.

Pilot ability recharge increase On reflect Effect on nearby allies Mid-level feature High-level feature Sold at workshops
Tank Some Restores some ship health Increases their resistance Group repair Improves recoil stability Haven, Tundria, Necrom
Commander More Recharges weapon energy Increases their resistance Increases weapon damage near allies Sonatus, Tundria, Necrom
Alliance Most Increases weapon damage for 5 seconds Doubles their weapon damage Increases weapon damage near allies Ashar, Necrom
The Alliance core is only available in level V, and can only be obtained by buying one at a workshop. It's very pricey -- about 8 to 10 times the cost of other level V core mods.



Special core mods

In addition to the primary core mods listed above, there are a couple of special core mods that you earn by completing campaigns. These are level V mods.

Completing the Atlas's Most Wanted (bounty hunter) campaign gives you a special Arboretum Core mod. I apologize for not having any further information on that one. Maybe someone who's completed that campaign can provide information. Edited to add: The Arboretum Core mod gives +100 handling, +100 energy, +1500 damage on reflection, and activates lasers when health becomes critical.

For Nintendo Switch players only, completing the A Wolf in Atlas campaign gives you a special Arwing Super Core mod. That core only fits in the Arwing body, and increases both handling and weapon energy (but not speed). As an extra feature, ricocheting an attack with a dodge move temporarily increases laser cannon damage, but I think you can only get a ricochet if you also have the Arwing Super Armor mod fitted.