The Forgotten Cellar half is very expensive for what it is, but its still a great bonus on top, especially if you can ramp using the left half
Six mana is probably too much for Constructed formats, but milling four cards is a nice little addition to the effect that might help it see play in reanimator decks
Her +1 ability reads Each player discards a card. Since it doesnt say anything about targeting or choosing a specific player, a player with hexproof would still have to discard a card
On the one hand, I think its good, it has nice stats, and being able to give it first strike is pretty nice
Im predicting that Legion Loyalty will become a mainstay of casual mono-white and Boros aggro decks and I look forward to all of the memorable combat steps that this will allow me to take with my own decks
That said, theres 15 cards in a pack, and players sometimes do Draft collectors packs, so theres nothing really stopping you from doing it