Wild Magic Notetags

<Custom Action Start Effect>
 //store current action and define skill types to trigger Wild Magic
 var magicSkills = [a, b, c, ...]; //replace [a, b, c, ...] with an array of skill types to trigger Wild Magic
 var action = user.currentAction();

 //if the skill can trigger Wild Magic...
 if (action && action.isSkill() && magicSkills.contains(action.item().stypeId)) {
  //define which Wild Magic effect will take
  user._randomRoll = 4 + Math.floor(Math.random() * 10); //replace these numbers as you see fit
  //apply the selected Wild Magic effect on the user
  user.addState(user._randomRoll);
 }
</Custom Action Start Effect>

//this part is optional, or can have if-else clauses for a case-by-case basis if you wish
<Custom Action End Effect>
 //if the Wild Magic effect ID was defined earlier...
 user._randomRoll = user._randomRoll || 0;
 if (user._randomRoll !== 0) {
  //remove the Wild Magic effect
  user.removeState(user._randomRoll);
 }

 //remove Wild Magic effect ID
 user._randomRoll = undefined;
</Custom Action End Effect>