You can farm the fragments from Asuma as jump training before Sorthina if you want. You won't do sorthina before a craft anyway.
To solo omati you need:
A transformation.
A good dragon (lvl100 bird/windrider) with soul regeneration to mount between ulti if you are a magical class to kill the boss.
For summary omati:
-Kill each mobs.
-Take the egg with a transfo and put it as far from the door as you can.
-The boss come attack the egg.
-Aggro the boss and reduce 10% of its hp to make it disappear (he teleports to the first door) without the mobs to notice you.
-Destroy the first door and make sure no mob come attack the egg.
-Destroy all the other doors. (Each last door is the new attraction point of the mobs, when you destroy them all, the attraction point is behind the last door)
-Transport the egg until just before the last door. (Just before the mobs see you at the left of the way)
-Transport the egg avoiding the mobs until the merchand in transfo + all buff speed you have + a shield if possible to not lose the transfo.
-Kill the boss. (you can't fail anymore as you've given the egg to the merchant. You can die as many times as you like in experimenting the boss. notice that his attacks always follow the same pattern)
Since you can't heal yourself, avoid all his attacks and be on your drag during the tornado.
As you see it's easy and you will manage it on your first time
. =)