Compute Shard

Summation
Damage based on the summation of user's individual HP digits.

Formula: user_hp_digits_added / 36.0 * ((atk * 4 - b.def * 2) * 4.0)

Average
Damage based on the average of the party's current HP.

Formula: party_average_hp / 1.5

Subtraction
Damage based on highest HP in party minus the lowest HP.

Formula: highest_member_hp - lowest_member_hp