Nah it's a simple move both pieces of the angel statue to the correct spot to use it. You walk forward and 4 buttons appear blocking Zenki in so he has to finish the puzzle. The boss won't appear if you don't have the Burst Necklace, and if you don't use the skill "Call on Ennsid"
I have no clue how to make a skill tree (can barely edit the menus look) I could make it so you choose the gender, though I'm more so leaning towards leaving them genderless unless choosing random since it gives a challenge. I plan on trying to add passive and quests. Might just rework all skills, and try getting magic based skills working.