Spell.dbc MiscValueA & MiscValueB

For a very long time i’ve tried to figure out how MiscValue works in spell.dbc, but no matter what i always run into a wall and no one knows.

Now i wanna learn how you find the misc value for a spell.

Lets say i have a spell that increases critical strike, i want to know what the misc id is for this and where it can be found, or attack speed.

Pretty much what im trying to do is a spell that increases overall crit chance in % and to do that i need the misc Value.

The meaning of miscvalues depends on the effects. It’s one thing in one effect and completely different thing in another effect. You don’t really “find” it, it’s already in spell DBCs.

Then how do i find what the valus stand for that has misc valus already in them?

Like for Aura mod rating there is a value for crit in x stat that increases crit, if i have 1000 crit and equip an item with my custom spell on it my crit will be increased to 1005 crit
(if the custom spell has 4 in base points and 1 in die sides). 
Now there should be a Value to do this in Percentage.

Also as someone put the value there then they have gotten it from somewhere and its defined somewhere.