Teaser: Hero points

Update: Hero Points have been overhauled. See next post.

Spending a hero point gains a character a reroll for any action. The player chooses whether to use the first roll or the reroll--or whether to spend an additional hero point for a third roll (any number of hero points may be used, subject to availability).

Characters can purchase hero points with DP (development points, which are earned via adventuring and training). The cost of a hero point depends on what the new hero point total will be. From scratch, a given total costs the square of the total (i.e., it costs 16 DP to have 4 hero points). If you already have hero points, the cost is the difference between the square of the new and old totals (e.g., if you have 2 hero points, you must spend 5 DP to to buy a third hero point, and 7 more to obtain a 4th).

Note: the DP cost of skill advancement is the same. For example, it costs 1 DP to obtain skill 1 (from zero; skill zero is termed "unlearned"); to advance from skill 1 to skill 2 costs 3 DP. To attain skill 10, the overall cost is 100 DP.

Expending a Hero Point lets you add a second roll to the normal die result.

For example, an attack is made by rolling d20* + Weapon skill expertise. This attack total is compared to the target's defence total (i.e., d20* + defence skill expertise). If the attacker uses a Hero Point, he increases his attack total by rolling another d20*.

Since base damage is the attack's success margin (i.e., the amount by which the attack total exceeds the defence total), using a Hero Point can be significant.
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*In Mailed Fist, the normal resolution roll not a d20. Instead, it is what I call a diff20. See the diff20 post.