I stand somewhat corrected. Here's the LotR rule book on blocks:
Each game has one of the following formats:
• Fellowship block – only cards from sets 1, 2, and 3,
• Tower block – only cards from sets 4, 5, and 6,
• King block – only cards from sets 7, 8, and 10,
• War of the Ring block – only cards from sets 11, 12, and 13,
• Open – all cards allowed, including set 9 (Reflections), using only sites from set 11 onward (Shadows).
• Standard – a tournament format similar to Open, but including the X-List (see the Current Rulings document, available for download).
Set 9 is in no "official" block.