Hibernate with enabled enhancer throws error at deployment

public class TornadoStrikeSkill extends SelfTargetSkill {
	private static final long serialVersionUID = 1123460060768124078L;

	public TornadoStrikeSkill() {	}

	@Override
	protected void executeSkill() {
		.....
		GameObjectService gameObjectService = BeanLocator.lookup(GameObjectService.class);
                // getting the characters from an EJB
		for(GameCharacter victim : gameObjectService.calculateVictims()) {
			
		}
	}

public class GameCharacter extends GameObject {
	@OneToMany(mappedBy = "caster")
	private List<Skill> skills = new ArrayList<Skill>();