His flipping from mono-green into black-green represented the curse bestowed upon him by the Chain Veil, which corrupted his power over beasts into something twisted and violent
The best, generally good cards that are great in this archetype: The self bounce, which requires the creature to be cast again, so it's not as good for tempo: The poison: Do you support blink
Five different sets across a full calendar year and the last piece wasnt confirmed until the Japanese Pokmon Center revealed card sleeves featuring the completed illustration

Set Contents Monster Black Witch Dear Bianca Star UR2 Snake Eye Hoight Birch N1 Snake Eye Excel N3 Snake Eye Orc N2 Snake Eye Fire Phosphorus SR2 Snake-eye Magna Drago UR2 Ash Blossom & Joyous Spring SR3 Maxx "C" SR3 Effect Veiler SR3 Magic Triple Tactics Talent UR1 Crime Treasure Hunting Darkness Demon SR3 Snake Eye Temple Snake Eye R3 Crime Treasure Snake Eye SR3 Snake Eye Chasing Drama N1 Bonfire SR2 Called by the Grave SR2 Trap Infinite Impermanence UR3 Crime Treasure of Betrayal - Silwia R1 EX S:P Little Knight SR1 Hiita the Fire Charmer, Ablaze N1 Linkuriboh N1 Pit Knight Ary R1 Accesscode Talker N1 Selene, Queen of the Master Magicians SR1 Apollousa, Divine Bow of Calling UR1 Topologic Trisbaena N1 Amphibious Swarmship Amblowhale UR1 Blame Princess of Gifted Fire UR1 Downerd Magician UR1 Divine Arsenal AA-ZEUS - Sky Thunder UR1 Ti-Fong, Star of Disaster UR1 LL-Assembly Nightingale N1 #GATCHA Deck Item ID: 1097349764

These are also useful ways to deal with indestructible threats, which green basically cant do otherwise