Math!

Math is go(o)d!


You have at least 2 dice (required for the feat), and you get feats at odd levels, so you can typically get this at level 3+, guaranteeing 3 dice at least.

With 2 dice, you have 16/36 (44.4%) chance of getting Level 1, and 2/36 (5.56%) chance of getting Level 2
With 3 dice, you have 198/216 (91.7%) chance of getting Level 1, 111/216 of getting Level 2 (51.4%), 54/216 of getting Level 3 (25%) and 15/216 (6.94%) of getting Level 4.

So from this non representative sample, it looks like Level 1 is going to be easy to get. Level 2 should be feasible with 4-5 dice, and higher levels will follow.


As another guesstimate, each die is worth 3.5 on average (via sums), so you need 10 dice for the average sum to be close to the Level 4 requirements. Level 9 would require 30 dice, and is therefore never going to be easy - it will require multiplication to reach even with 17 dice (when 9th level spells are available), so it's not going to happen too often.

With 2 dice, the average sum is 7, and Level 1 happens about half the time - not bad.
With 3 dice, the average sum is 10.5, and Level 2 happens about half the time - again, not bad.

So it looks reasonable to assume that Level 4 will work about half the time when there are 9-11 dice, Level 5 is half the time around 12-14 dice, and so forth. This does mean that a Level 7 spell is never going to be a sure thing - if the assumption holds.