Program: 159524
Project: 159524
Buggy source:
@Override public boolean replaceEvent(GameEvent event,Ability source,Game game){
  GameEvent preventEvent=new GameEvent(GameEvent.EventType.PREVENT_DAMAGE,source.getControllerId(),source.getId(),source.getControllerId(),event.getAmount(),false);
  if (!game.replaceEvent(preventEvent)) {
    Permanent targetCreature=game.getPermanent(source.getFirstTarget());
    if (targetCreature != null) {
      int damage=event.getAmount();
      if (event.getAmount() >= this.amount) {
        event.setAmount(damage - this.amount);
        damage=this.amount;
        this.used=true;
        this.discard();
      }
 else {
        event.setAmount(0);
        this.amount-=damage;
      }
      if (damage > 0) {
        game.informPlayers(new StringBuilder("String_Node_Str").append("String_Node_Str").append(damage).append("String_Node_Str").append(targetCreature.getName()).toString());
        game.fireEvent(GameEvent.getEvent(GameEvent.EventType.PREVENTED_DAMAGE,source.getControllerId(),source.getSourceId(),source.getControllerId(),damage));
        Player targetPlayer=game.getPlayer(source.getTargets().get(1).getFirstTarget());
        if (targetPlayer != null) {
          targetPlayer.damage(damage,source.getSourceId(),game,false,true);
          game.informPlayers(new StringBuilder("String_Node_Str").append("String_Node_Str").append(damage).append("String_Node_Str").append(targetPlayer.getName()).toString());
        }
 else {
          Permanent targetDamageCreature=game.getPermanent(source.getTargets().get(1).getFirstTarget());
          if (targetDamageCreature != null) {
            targetDamageCreature.damage(damage,source.getSourceId(),game,true,false);
            game.informPlayers(new StringBuilder("String_Node_Str").append("String_Node_Str").append(damage).append("String_Node_Str").append(targetDamageCreature.getName()).toString());
          }
        }
      }
      return true;
    }
  }
  return false;
}

Fixed version (ground truth):
@Override public boolean replaceEvent(GameEvent event,Ability source,Game game){
  boolean result=false;
  int toPrevent=amount;
  if (event.getAmount() < this.amount) {
    toPrevent=event.getAmount();
    amount-=event.getAmount();
  }
 else {
    amount=0;
  }
  GameEvent preventEvent=new GameEvent(GameEvent.EventType.PREVENT_DAMAGE,source.getControllerId(),source.getId(),source.getControllerId(),toPrevent,false);
  if (!game.replaceEvent(preventEvent)) {
    Permanent targetCreature=game.getPermanent(source.getFirstTarget());
    if (targetCreature != null) {
      if (amount == 0) {
        this.used=true;
        this.discard();
      }
      if (event.getAmount() >= toPrevent) {
        event.setAmount(event.getAmount() - toPrevent);
      }
 else {
        event.setAmount(0);
        result=true;
      }
      if (toPrevent > 0) {
        game.informPlayers(new StringBuilder("String_Node_Str").append("String_Node_Str").append(toPrevent).append("String_Node_Str").append(targetCreature.getName()).toString());
        game.fireEvent(GameEvent.getEvent(GameEvent.EventType.PREVENTED_DAMAGE,source.getControllerId(),source.getSourceId(),source.getControllerId(),toPrevent));
        Player targetPlayer=game.getPlayer(source.getTargets().get(1).getFirstTarget());
        if (targetPlayer != null) {
          targetPlayer.damage(toPrevent,source.getSourceId(),game,false,true);
          game.informPlayers(new StringBuilder("String_Node_Str").append("String_Node_Str").append(toPrevent).append("String_Node_Str").append(targetPlayer.getName()).toString());
        }
 else {
          Permanent targetDamageCreature=game.getPermanent(source.getTargets().get(1).getFirstTarget());
          if (targetDamageCreature != null) {
            targetDamageCreature.damage(toPrevent,source.getSourceId(),game,true,false);
            game.informPlayers(new StringBuilder("String_Node_Str").append("String_Node_Str").append(toPrevent).append("String_Node_Str").append(targetDamageCreature.getName()).toString());
          }
        }
      }
    }
  }
  return result;
}