Six mana to remove up to three creatures from the game is a steal, even if it leaves behind a few small bodies on your opponents boards
Drawing random cards from a shuffled deck makes gameplay balanced and less predictable and more exciting, but some cards with special abilities, like scry, can skirt the rules a little
Even if we have a single dragon on board instead, Draconic Lore and Winged Words are just very efficient draw that require little setup
If you flip a second Illuna, you can add it to hand and then mutate it onto the first one for a double trigger (and no legend rule!) Its harder to see exactly what to do with Vadrok, Apex of Thunder , since one of the best spells in Jeskai to recast Deafening Clarion will also kill Vadrok unless you mutate it under something with better stats
The Seriema has real upside as a spacecraft that can eventually do some great flying damage and protect those legendaries by granting indestructibility