Here are a couple of examples of “actions” based on the skill-based d20 system I developed a while ago, combined with the Actions framework discussed yesterday. One is a spell, one a “supernatural ability” and one a “mundane” (and hideous) special ability. The Cost line in each description gives the attribute against which damage is done if the action fails. The cost is always 1 wound. In my conception of magic, arcane magic incurs a physical cost (it is exhausting) while divine magic incurs a mental cost (it drives you a little bit.. irrational and loopy). So failed arcane spells incur a wound against strength, while failed divine spells incur a wound against intelligence. In this system, a critical is achieved by a roll of a 20, at which point 2d10 are re-rolled and added to the previous roll to get a new total. On rolling a critical, all maximum effects (damage, rounds of duration of effect, etc.) are increased by some amount.
Conditions: Must have one hand free and be unencumbered, not wearing metal armour. Target must be within sight, and have at least one arm or other limb.
Skill check: Intelligence (Offense) vs. Target Strength (Defense)
Critical: Yes (Double)
Effect: This spell attempts to tear off the target’s arm. It does maximum damage 7, and the target is stunned for one round plus one round per point of success (maximum 7, double on a critical). The target is also bleeding (1 wound/rd) until healing is administered. The target loses all use of one arm, either temporarily (due to massive injury) or permanently (due to amputation) at the GM’s discretion.
Type: attack, reaction
Conditions: Attacker must be visible to the targets of the action, who must be allies of the target. Target must have been reduced to 0 hps in this round, by the PC or one of his/her allies.
Skill check: Charisma (Offense) vs. Charisma (Defense)
Effect: The character turns an opponent’s death into a lurid display of horror and gore. Any ally of the dying enemy who witnesses his/her/its death is shaken for 1 rd plus 1 rd/point of success. The target experiences a -2 penalty on all actions and will attempt to avoid combat with the character if possible. If the target is already shaken due to witnessing a hideous death in this engagement by this character, they move from shaken to terrified, and will immediately attempt to flee the battle.
If this action is being used on an enemy the character did not kill, apply a -2 penalty to the skill check.
The GM may choose to allow the player to describe the type of hideous death for an attempt at a bonus on the skill check. This is strongly advised! Note that failure to successfully terrify the target merely makes the PC look like a bloodthirsty maniac (charisma damage).
Skill check: Wisdom (Use) vs. DC 20
Effect: The PC conjures an infernal essence to enhance their weapon or armour, giving a +1 to maximum damage or damage reduction for 1 min + 1 min/pt of success (maximum=character level). This is an infernal effect, so can be dispelled by demon-binding or abjuration effects, but not by magic-dispelling effects. It is usually visible as a faint glow and/or feeling of discomfort or unpleasantness surrounding the PC.
Higher-level versions of this effect are possible, and give an effect equal to the level of the action.