For those interested in the nature of the later, harder words but not willing to work through the earlier sets, here are the ones from my run:

Level 0: Core Basics Abundant, Baffle, Candid, Dwell, Emerge, Frugal, Generic, Hinder, Impartial, Jovial, Knack, Lucid, Meager, Naive, Obsolete, Peculiar, Quench, Refute, Seldom, Tedious, Unique, Valid, Wary, Yearn, Zeal, Adequate, Barren, Coarse, Diligent, Esteem, Fickle, Gloom, Hoax, Ignite, Jolt, Keen, Linger, Mend, Numb, Omit, Pledge, Quota, Rural, Soothe, Toxic, Urge, Vow, Witty, Yield.

Level 1: Intermediate Acumen, Benevolent, Complacent, Dilapidated, Eloquent, Fabricate, Gregarious, Hypothetical, Imminent, Juxtapose, Lethargic, Meticulous, Nostalgia, Oblivious, Pragmatic, Reiterate, Scrutinize, Tentative, Ubiquitous, Verbose, Wane, Aesthetic, Bolster, Candor, Defer, Elicit, Furtive, Glut, Heed, Impeccable, Lament, Modicum, Notorious, Opulent, Plausible, Resilient, Stagnant, Trivial, Viable, Zenith.

Level 2: Advanced Alleviate, Breviary, Cacophony, Deferential, Ephemeral, Fastidious, Garrulous, Harangue, Iconoclast, Juggernaut, Laconic, Magnanimous, Nefarious, Obsequious, Paradigm, Recalcitrant, Sanguine, Taciturn, Ubiquity, Vacillate, Winsome, Zephyr, Abase, Banal, Capricious, Debilitate, Ebullient, Facetious, Gaikwar, Hackneyed, Idiosyncrasy, Jargon, Kindle, Labyrinth, Maverick, Narcissism, Ostracize, Palliate, Quagmire, Rancorous, Sagacity, Tantamount.

Level 3: Expert Abstemious, Bellicose, Chicanery, Deleterious, Enervate, Fatuous, Gauche, Hegemony, Inculcate, Jejune, Kowtow, Lugubrious, Mawkish, Nonsectarian, Obdurate, Pernicious, Quotidian, Recapitulate, Supercilious, Tempestuous, Unctuous, Vehement, Winnow, Xenophobe, Ziggurat, Acquiesce, Bombastic, Circumlocution, Desultory, Equinox, Fiduciary, Gerrymandering, Hubris, Incognito, Kinetic, Loquacious, Metamorphosis, Nihilism, Orthography, Precipitous, Quasar, Reparation, Soliloquy.

Level 4: Grandmaster (The Obscure) Accoutrement, Brobdingnagian, Crepuscular, Defenestrate, Equanimity, Flibbertigibbet, Grandiloquent, Hippopotomonstrosesquippedaliophobia, Ineffable, Jingoism, Kerfuffle, Logorrhea, Mellifluous, Obfuscate, Panacea, Quixotic, Rococo, Sesquipedalian, Tergiversate, Ultracrepidarian, Vicissitude, Weltschmerz, Xeric, Yclept, Zeitgeist, Absquatulate, Bumbershoot, Callipygian, Dord, Ergophobia, Fartlek, Gobbledygook, Houghmagandy, Interrobang, Kakistocracy, Lollygag, Mumpsimus, Nudiustertian, Omphaloskepsis, Pogonotrophy, Quire, Ratoon, Snollygoster, Tittynope, Ucalegon, Vagitus, Widdershins, Xylopolist, Yarborough, Zenzizenzizenzic.