If you have a full hand, using this ability will take up your loyalty, but then do nothing, rather than just not working at all.
Further, if you have already drawn all the werewolves in your deck, or fetched them with her ability, you will not be able to use her 2nd ability at all, until you have drawn out all the rest of the cards in her deck. That means that she can only use it 4 times at most if you are running 1 werewolf in your deck, 8 times if 2, etc. until you have drawn thru your cards.