I did a playthrough where I decided to go "toolbox" mode. I invested at least one point in memory every other level, and spread my skill points across multiple types of skills in order to maximize the different skills I can put on each character.
By the end of the game, every character had fortify, regeneration, and armor of frost, followed by all the appropriate skills for whatever build I had decided to go with on that character.
The result of it was that combat began to feel trivial. The combined efforts of multiple enemies full turns could be nullified by a couple AP on one character, up to and including the CC effects the enemy may have broken through my armor with. I even noticed that my characters were all almost always at full vitality because I could casually use an extra AP to cast regeneration on someone. Were I to do that tactic again, I wouldn't even feel bad about taking the "+10% accuracy and damage at full vitaltiy" talent, which I previously avoided in favor of more reliable bonuses.
And all of this was possible with just one point in hydrosophist and one point in geomancer on every character, an investment of just 2 levels' worth of points, while still developing their strengths through stats. If I were to propose a solution, I would say that maybe you should increase the AP cost of such healing abilities to 2 AP each, or remove the "cure ailment" aspect of it, or do some solution where the base healing of such abilities are very low, and the "extra healing" percentages gained through the hydrosophist and geomancer skills are much higher.
One thing that I would love to test but cannot at the moment is how this strategy fares at higher levels. It may just be that this strategy serves very well on the island but would fail me later on, but from what I've seen I only know that this strategy makes the party extremely durable and the enemy runs out of gas, and you give up very little in terms of character advancement.
