The second, more obvious reason that cubes frequently take advantage of proxies is that cubes tend to include expensive cards
In fact, having played it a few times with middling success, Apprentice Wizard is pretty handy when it survives long enough to produce mana
Brainstorm Brainstorm is not only difficult but also straight-up very powerful as a card - arguably one of the strongest cards ever printed
In a fast aggro deck, 4 warped damage out of nowhere really hurts, and later, your opponent has to deal with the real dragon
A lot of the new cards in this deck bring plenty of support for the monarch theme: Denethor, Stone Seer, Archivist of Gondor, omer, King of Rohan, Champions of Minas Tirith, Forth Eorlingas!, Crown of Gondor, Fealty to the Realm, and Oath of Eorl all bring some much needed support for the archetype, and in varied and interesting ways