I'm a little bit later to the party, per usual, but I am just now starting to purchase Chaos Legion packs and then stash them on my hive-engine account until I can open them.
I'm trying to buy at least one per day, maybe two if I can swing it but with 24 days left on the Chaos Legion pre-sale I'm hoping to at least get to 50 packs purchased to get one of the Doctor Blight promo cards. I foresee that cards being VERY expensive down the road and I have a feeling that this is going to be the only way that I've ever going to have a chance to get one of them through the pre-sale promo purchases.