Adding same value to variables in does each repetition of command

ETC Microsoft Windows
1

So, I have this command:

mkdir rolled

for %%x in (*gif) do convert %%x -roll +2+6 %%x|move %%x rolled

I'd like to have the +2 and +6 accumulate here.
In each new gif tackled, it should increase by the amount: +2 (for x) and +6 (for y)

Is this possible?

I'm on Windows, DOS.