he is at the end of desolation... you need the key though

-same attribute item adds up the level( fire lvl1 + fire lvl1 => fire lvl2, lvl1 + lvl2 => lvl3)

-some attributes cancel each other (fire lvl1 + ice lvl 1 => fire lvl0 + ice lvl0)

-synthesis costdoubles each time you perform syntesis
(so you better be strategic keeping the cost down)

-set the itemyou want to keep at first synthesis slot (dagger + ring => dagger, hammer + mace => hammer)
(so better hp, sp items must come first)

-item + red portion(small) empty the last option slot, (medium) empty last two, (large) empty last three slot

-item + white portion empties all slot

-weapon + orange portion=> increase damage 30% (better use it at high level weapon like 1000)

-armor + sky blue portion=> increase health 20%

-item + electric shocking devise => increase otion slot

-SP generating item + SP generating item => increase SP generating rate

-armor + SP generatin item => SP consumption decrease

-weapon + low SP weapon => SP consumtion decrease (100 SP consumpting hammer + 20 SP hammer => 60 SP hammer)
(going back toact one casual dificulty and gettinglow level weaponsis one way to reduce your SP usage)

-option weapon syntesis decrease HP and damage
that means no option weapon doesn't effect HP and damage
so the best strategy is:
no option high damage weapone + high lvl item