Went on a hiatus after The Dark Below and think I may have chosen to wait too long to come back because it seems if I am looking to still play the game in any meaningful way I will need to grab both House of Wolves and the new TTK expansions. My question concerns the array of options when it comes to purchasing these packs. Can I not buy both separately or will I be forced to buy one of the bundles including items I already have (base game and TDB)?