Immortal Disappear Rate

i need to know how to change the immortal stone blue rate of disappearing from the item
explain
when you wanna make a plus Ex : +7
you put an immortal stone
if it failes
immortal can be disappear from the item
and can be still on the item
how can i change this rate ?
any idea ?

I think its inside the game server. But don't know what its opcode to change it :/

This is just the alchemy rate. If your item just failed the immortal stay. If it was going to destroy the immortal is used instead so it's gone. It's just the alchemy rate. There's no rate for immortals.

So how can we know the destroy rate vs the failed rate !!

U said it may fail or destroy.. so there is a destroying rate..[ I think ]