I long time ago, (about a year) I mentioned a system for chart based spellcasting. The idea was that you rolled some custom dice to consulted the chart to see if it was successful. No two charts are the same, etc.
The issue was that it used dice that you can't really buy anymore, dice from a game called Paydirt.
While working on my FASERIP Hack it occurred to me that I could use 3d6 instead of three custom dice. I also made the charts similar to Vedic Squares.
Looking at the Pic, 1 through 7 represents the spell level. The left column has the values 3 through 18. Roll 3d6, look at the result and match it with the spell level of the spell you want to cast. If the square is black, the spell fails.
Hope to have more soon.