I want to creat a state for a curse spell that the state reduces the a element resistant of enemys.but in data base only have guard to element.
SO help me

Well hi. And welcome to RRR, its best if you go to the Introductions forum to let us all know we've got a new member here.

Now for your question.

This sounds like something you'll need a script for. I looked into my VX file. The only time I have custom stats is when I have a script. Try searching our scripts or posting the the Script Suggestions forum for help.

You're gonna need a script to implement this.

The easiest one I can think of is Yanfly's Custom Element Affinity. You can have states that manipulate elemental weaknesses/resistances very easily.