What it does is that it can actually change into a creature at any time and provide aggression that is able to synergize super well with a wide range of decks
Plus, its rebound ability generates additional value as you can cast it for free from exile on your next upkeep
He is a flash 2/2 for four mana and can bounce on arrival to the battlefield any spell or permanent, even a land
Then resolve the Guide of Souls trigger first, and have the Shrieking Drake bounce itself to your hand
Whereas Dominaria had excellent common removal spells in white, blue, black, and red (with multiple good options across all colors and mana costs, excepting green), Guilds of Ravnica consenses most of its best common removal in black, blue, and white
The AI needs a single clear subject to anchor the creature design multiple subjects cause the feature mapping to blur between them, producing a generic result instead of a recognizable transformation