This is because defender simply prevents a creature from attacking
Dare I say, it's a balanced dragon spirit
This is just inherently true for many creatures, because even better than one strong creature is two strong creatures
Other cards found in the Ursulas Return set that feature this new approach to the Shift keyword include Flotsam & Jetsam, Entangling Eels - which a five strength/five health card that requires two cards to be discarded - Diablo, Devoted Herald, a card that requires players discard an action card, Li Shang, Valorous General - with players needing to discard a character card to Shift it in - Olaf, Carrot Enthusiast, a Sapphire card that can be Shifted by discarding an item card, and steel card Aladdin, Brave Rescuer: which requires that a location card be discard for it to be Shifted
Each quest will reward you with a deck that combines two colors, of which there are 10 possible combinations