The Statue: Naga Sadow decoration can be dropped from Acolyte's Shadow Packs, which were released on the Cartel Market and bought with Cartel Coins. Cartel Packs, including the Acolyte's Shadow Pack, include a random selection of items from the Acolyte's Shadow collection of items. You aren't guaranteed to get a Statue: Naga Sadow decoration from a Acolyte's Shadow Pack, but it is one of the few ways to get a Statue: Naga Sadow deco apart from buying it on the GTN from another player.
If you're looking to get a Statue: Naga Sadow, the easiest way to get it is to head to the Galactic Trade Network (GTN) in SWTOR and buy it with credits from another player. If it's very rare and not available on the Cartel Market, you could try buying from the GTN and hope you get it.
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