Myriad didn't make sense in a 1v1 environment, so it was repurposed into the digital-only double team mechanic, which captured the feel of myriad well enough
Theres also Gollum, Riddle Master
Think of Delta Species as the old-school version of Tera Pokemonjust without the fancy disco-ball crystal hats
Now, it works well alongside cards like Bolt Hound, which makes all plant tokens attack with +1 damage, and Return of the Wildspeaker, which gives all non-human creatures +3/+3
Those seeking to use this tremendous trio are recommended to include Arceus & Dialga & Palkia in a Dragon-type deck
Theros was the first set with ten two-color archetypes without factions in it, and Erik found his solution