Rise Eterna

Each character has one "ultimate skill". It is therefore required to have at least 10 party members to unlock this achievement. Skills are unlocked in the "Skill Tree" section and the ultimate skill is always the skill in the middle of the upper section (the section is called "Hero Skills"). There is a small crown on top of the ultimate skill square. (The skill with the wings around the square at the far right does not have to be unlocked for anybody, but I would appreciate, if anybody could check if the skill at the far right also increases progress for this achievement).

The character needs at least 8 or 9 skill points to unlock the ultimate skill. Start on the left and completely level up the first Hero Skill. This will unlock two further skills on the right. Completely level up ONE of these skills to reach the ultimate skill, which only needs a single skill point. Do not forget to press to accept the spent skill points. You may switch through your characters by pressing or , spent skill points and accept just once at the end.

Skill points are earned by completing missions, but only for characters, who are in your party. You get one skill point for one mission and one additional skill point for replaying a map (but just for the first time). Every new party member joins with as many skill points as you have completed story missions. This means that after mission 9 basically every new character will already have enough skill points to unlock the ultimate skill right away.

Note that there is another achievement for fully unlocking one half of the skill tree without unlocking any skill of the other tree. I recommend to avoid the "Generic Skills" until late in the game. The ultimate skills make each character unique and will influence how you play that character.

For a description about when it is the first time you could have 10 characters in your party, check the spoiler: