Hook: Floor Medium (Blue Square)The Toxic Cauldrons decoration fits into a blue medium square floor hook.
Hook: Floor Large (Purple Square)The Toxic Cauldrons decoration fits into a large purple square floor hook.
How to Get a Toxic Cauldrons Decoration
Cartel Pack Decorations
The Toxic Cauldrons decoration can be dropped from Discord PacksUltimate Cartel Packs, which were released on the Cartel Market and bought with Cartel Coins. Cartel Packs, including the Discord PackUltimate Cartel Pack, include a random selection of items from the Discord Ultimate Cartel collection of items. You aren't guaranteed to get a Toxic Cauldrons decoration from a Discord PackUltimate Cartel Pack, but it is one of the few ways to get a Toxic Cauldrons deco apart from buying it on the GTN from another player.
If you're looking to get a Toxic Cauldrons, 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.