LFR Campaign final ruling on content from Into the Unknown: the Dungeon Survival Hanbook
Chapter 1: This entire chapter is a player resource for LFR. To be clear, the new class powers and skill powers on pages 52-71 do NOT require the PC to be a member of any particular organization or have any particular theme or background. For example, you don't have to join the Deep Guides (page 56) in order to choose the writhing earth power or any of the other powers in that section.
Chapter 2: The dungeon-specific backgrounds are for places not located in the Forgotten Realms, so those backgrounds are not legal. (The Temple of Amun-Re has appeared in the Forgotten Realms, but it doesn't have a background associated with it.)
Chapter 2: The Haunted feat (page 102) is legal in LFR.
Chapter 2: The mundane adventuring gear (table on page 114) and the alchemical items listed with a rarity of Common on pages 116-117 (longbreath, phantom ink, stone eater, and violet phosphor) are considered player resources. Aboleth slime (Uncommon) and pacification dust (Rare) keep their published rarities and should be treated as magic consumable items instead of as alchemical items, because otherwise their rarity would have to be reset to Common per the LFR Campaign Guide ruling that all alchemical items are Common. (We will revisit that wording in the next update to the LFR Campaign Guide; at the time we wrote it we had no reason to believe that a published source would ever include an Uncommon or Rare alchemical item.)
Chapter 3, Appendix 1, Appendix 2: These chapters / appendices contain no LFR player resources. (In particular, the Scrolls of Power on pages 145-147 are NOT legal in LFR.)