I love the design of this card. 3 damage in 1 card is incredible, but part of what makes allies the best card type in the game is the ability to soak up a big attack with their last point of health. This makes for a fascinating decision both in how we choose our allies during deckbuilding and in gameplay. You are obviously more likely to use Last Stand if your ally is already a huge beater and you would have wanted to attack with it anyway. I personally look forward to using this with Goliath.
Conclusion: Last Stand makes it into the beautiful gray area of Champions cards that are neither unplayable nor a staple but should always be in consideration when making your Leadership deck.