I had to grind (after completing everything in game) for two extra levels to get 2 ascension point to complete one color + required other color spells. Did the grind in Shrouded realm and Mt. Dresnyr because there are more mini-boss type enemies appearing in these area.
After unlocking all spells in one color, Just Reset specs (you should have more than enough gold) and allot the points to other color tree to unlock all achievement.