'I know, I'm crazy.'
Anti-Tarr is a plant that has an un-creative name.
Feeding it to Tarrs makes them a random largo.
Feeding it to largos makes them be able to be a trielemental largo, trielemental means you can give them another plort without the formation of a Tarr.
You can continue giving the largos more Anti-Tarr, and in turn, more plorts. This allows for combinations such as a Pink-Rock-Phosphor-Tabby-Boom-Honey-Puddle-Rad octoelemental.