Why makes it a chase card: Iconic status as one of the original 151 Pokemon
Terastodon, Woodfall Primus, and Primeval Titan are probably the best cards for the "big green creature" role, but Simic Sky Swallower and Broodmate Dragon can serve the role as well, although they require greater deck manipulation to be able to hard cast should you draw either of them before finding your Natural Order
As one of the most valuable cards from Dragon Frontiers, Mew Star can be difficult to find, causing massive shifts in TCGplayer sales data
Deathrite Shaman is a little slower and more vulnerable than Courser, he also loses his other utility and costs you some mana should you be using him for life
Throw those into the mix, and there are over 600 cards to collect - it's bonkers
6 Demon Of Dark Schemes Powerful, But Out Of Place Dark schemes indeed