Allagan Tomestones

[Wysteria]

Desyn skills?

Desynthesis is, an action to breakdown items in order to gain its components, which may only be able to obtain through the desyn process.
for example, demimateria, which is used for making "master" recipe crafting. Or elemental core from primal weapons, which is used to make new primal weapon (you can go search for moogle weapons on marketboard)
so, basically, if you want to obtain special items, you'll need to breakdown (mostly) high level items, and this has chances to fail, so you'll need to breakdown low lv stuffs until you're good enough to breakdown big stuffs (max at lv 100)