Contributed by Alan Gunhouse (aka Timbender)
Magic Core
Of all the cores, the Magic cores are the ones with the least weaknesses.
All cores have 2 other core types that resist their power, that part seems balanced. However, when it comes to other gear, there is currently only one thing that resists Magic (the Phrenic Leggings).
The Magic core is resisted by the Mental Core and the Elemental core. Both of these cores are resisted by many items. For one example, the Mental core is resisted by the Kang Sheng, which is arguably one of the most common Morphon items bought. This means while a person with a Magic core can easily shield against their weaknesses, others can not easily shield against Magic.
Just yesterday I was fighting someone with a Magic core, and they had a high resistance to just about everything but Magic. I was looking for a way to beat them for Fight Club. Now, since they had higher HP than me and apparently also higher combat values I could not win, but in the process I tried nearly every core against them.
Given that there is only a slight advantage to having gear that matches your core, there is no logical reason not to pick a core that has far more strengths than weaknesses.
Now personally I have only one Morphon core, which is Supernatural. I suppose I might have had different results with other Morphon cores, but I am pretty powerful generally for a budget character.
We can hope that the Developer has plans for items to resist magic, but until they are in play, you will continue to see the majority of the high-level characters using magic cores.
The point of this? As best I can tell, if you are a new player looking to invest in a core, it should be a Magic core. There is nothing else that really compares in bang for your buck.
Mental Core
As an experiment, I decided to try using Morphons to buy a second core. Since my first Morphon core is Supernatural, I decided to try the Mental core next.
On paper, it looks good, it should provide defense against Magic and Elemental attacks while being weak to what my Supernatural core is strong against. In addition, it has Stun and Weakens Foes Blocking by 15%.
The results were entirely disappointing. Every foe who is using a fairly high-level magic or Elemental core I encounter has a 40% resistance to Mental, which is higher than the resistance to Magic from the core of 30%.
As the Mental Core offers no bonus to life or attack, I was hitting far less often and doing less damage with the Mental core than with Supernatural, and was more easily defeated.
I would not generally recommend the Mental Core for high-level play.
Supernatural Core
I have mainly been using Supernatural cores since I started. There are 2 available for purchase and 1 free one, which makes it unusual.
Most Supernatural cores, in addition to the resistances they grant, also increase both Strike and Life. This is good for most battles.
There are a fair number of Supernatural gear items available, with means you will probably be able to get a good damage bonus.
There are defenses against the Supernatural out there, so you might run into enemies that you do half damage or less against. The additional strike bonuses tend to compensate to some extent (hitting more means that even if the enemy is hurt less each time it adds up eventually).
All in all, I am happy with my Supernatural cores, if I were a low-level player, I might advise not buying one for crystal though, the one you get for free from the Options Oracle mission is better.
For Morphons, the core is possibly the best attack core overall.