Time to learn. How you knew to put your little d*** inside your girlfriend's hole? Someone is teaching you? Nop. Life does. Same here.
Find which file work for you DispellBySlot or Cancel e.t.c in your datapack and on top of the
public void onStart()
add a simple list ex. final List<BuffInfo> canceled = new ArrayList<>();
Now read the code and see where it stop the effects. Example
effectList.stopSkillEffects(true, entry.getKey());
and bellow that add your spell into your list.
Now make a new threadpool like:
ThreadPoolManager.getInstance().scheduleGeneral(new ReturnBuffTask((L2Playable) info.getEffected(), canceled), 10 * 1000);
Now create a new class named ReturnBuffTask.java and in constructor declare the L2Playable and the List as parameters.
in:
@Override
public void run()
it will be called once the time pass of your threadpool and runnable is executed.
In there do a for to your list and add the skill back to the playable. Simple as that.