They could implement the following rules to gain SP. You have to earn atleast 2 points from the bottom to get SP.

1 Point: Perform enough damage to remove at the minimum 6.33% of the monsters total HP.
1 Point: Perform a Buff or Defensive Buff that affects the fight. (Casting Stone skin that gets worn out by damage Taken. Using a skill that modifies another skill)
1 Point: Use enough ability's and spells that you heal 25% of your total HP as damage (Must heal actual damage taken.)
2 Points: Use a reflex skill that requires outside input to perform (Feint, etc.)