The most expensive cards on the Reserved List come from the earliest years of the game: cards from Alpha , Beta , Legends , Arabian Nights , and Antiquities , primarily
And so-on
Her other abilities are solid too, especially her game-winning ultimate, but you dont even need to hit Lilianas ceiling to make her well worth playing
Morophon is a seven mana colorless Shapeshifter that lets you choose a Creature type when it enters, and then makes all of your spells of that type cost WUBRG less to cast, this only reduces the colored mana you pay, and it even gives those Creatures a +1/+1 boost
The deck is aggressive, and the idea is to build your board presence within the first three turns to then pump your creatures or remove blockers
Last but not least, some cards can use hybrid mana to pay for their activated abilities, or as an additional cost to their triggers