Synthesis is one of the most important parts of creating a strong army. Powerful skills such as the shifts, tricks, and spirits, grant a large advantage in battle, to the point where many players would rather use a UC army with high leveled skills than a SR army with only level 3 and 1 skills. Synthesis can be performed in the unit menu, and costs either 20 DP or 50 CP.
To enhance (level up) a skill, you need another monster of the same type (including rarity).
To learn a skill, you need a monster which provides the skill you want. Each monster gives 3 different possibilities to learn at once, with a 35% chance for the first, 10% for the second, and 5% for the last (55%/15%/10% with CP). What position the skills are in depends on the skill and level of the skill of the monster, rotating every 2 levels with a new one available at level 7. Refer below for information on how to get what skill and what skill gives what. For additional information about synthesizing, go to the Unit screen page.