DMM is already reserved for Deathstalker's Mount Mod.
Ah, drop after several levels. Gotcha. Here is a horrible way to do it:
Note the if-else function:
iif(cond, A, B)
This means, if cond is true, return A. Else, return B. You can naturally put other functions in for A and/or B.
Now to apply it:
40 - iif([%Level%] >= 5, 20, iif([%Level] >= 3, 10, 0))
This will make it:
L1: 40
L2: 40
L3: 30
L4: 30
L5: 20
L6: 20
L7: 20
...
Hmm... a possibly less crazy way that gets the same progression:
iif([%Level] >= 5, 20, iif([%Level%] >= 3, 30, 40))
Or, as a purely aesthetic issue, if you want to see decreasing sizes, just invert:
iif([%Level] < 3, 40, iif([%Level%] < 5, 30, 20))