Sunavalon Therions is a combination of 2 archetypes, Sunavalon focuses on Plant-Type Link monsters surrounding around Sunseed Genius Loci, and Therions is all about turbo'ing out Regulus and getting his negates, and as the secondary part of the Therions Engine is a Plant monster makes the two work very well together.
For the decklist, we have a Sunavalon package of 3x Sunseed Genius Loci, 1x Sunseed Twins, 2x Sunvine Sowing, 1x Sunvine Shrine, 1x Bloom, 1x Drytrentiay, 1x Melias, 1x Sunvine Thrasher, 1x Sunvine Healer, and 1x Dryas, we have a Therions package of 3x King Regulus, 2x Lily Borea, 1x Duke Yul, 1x Bulls Ein, 2x Endless Engine Argyro System, and 3x Discolosseum(and 1x Terraforming for it), for the rest of the Main Deck, we have a Handtrap lineup of 3x Ash Blossom, 2x D.D. Crow, and 2x Veiler, 3x Parallel eXceed, 1x Rose Girl, 3x Lonefire Blossom, 1x Aromage Laurel, 1x Spore, 3x Unexpected Dai, 1x One for One, 1x Called By, and 1x Humid Winds, for the rest of the Extra Deck, we have 1x Ruddy Rose Dragon, 1x Baronne de Fleur, 1x Black Rose Dragon, 1x Periallis, 1x Aromaseraphy Marjoram, 1x Garden Rose Maiden, 1x Hyperyton, 1x Underworld Goddess, 1x Benghalancer, and 1x Aromaseraphy Jasmine.