As one of the best promo sets ever, this card from Southern Islands is likely to remain Onix's most valuable card.
In our final game my Factories and his City of Brass lowered his life quickly and he never got a significant board presence
Along with that, it also has Vigilance, Trample and Haste - which means it can not only attack the turn it comes in, but also defend even if it does attack

Kaza Wizard Tribal Kaza, Roil Chaser | Illustration by Ekaterina Burmak Commander (1) Planeswalkers (2) Kasmina, Enigmatic Mentor Ral, Storm Conduit Creatures (25) Aphetto Alchemist Apprentice Wizard Archmage Emeritus Azami, Lady of Scrolls Cyclone Summoner Docent of Perfection Dualcaster Mage Fatestitcher Goblin Electromancer Guttersnipe Harmonic Prodigy Information Dealer Laboratory Maniac Malevolent Hermit Manaform Hellkite Niv-Mizzet, Parun Nivix Guildmage Overwhelmed Apprentice Riptide Director Siren Stormtamer Stonybrook Banneret Storm-Kiln Artist Triskaidekaphile Veyran, Voice of Duality Vodalian Arcanist Instants (15) Abrade Brainstorm Comet Storm Cyclonic Rift Deflecting Swat Dramatic Reversal Goblin Wizardry Increasing Vengeance Invert // Invent Narset's Reversal Pongify Rapid Hybridization Reality Shift Refuse // Cooperate Swan Song Sorceries (16) Brass's Bounty Crackle with Power Doublecast Epic Experiment Expressive Iteration Expropriate Finale of Promise Finale of Revelation Invoke the Firemind Jaya's Immolating Inferno Mana Geyser Sea Gate Restoration Solve the Equation Soulfire Eruption Step Through Tasha's Hideous Laughter Enchantments (2) Artifacts (6) Arcane Signet Geistflame Reservoir Herald's Horn Isochron Scepter Pyromancer's Goggles Sol Ring Lands (33) Base Camp Desolate Lighthouse Island x13 Maze of Ith Minamo, School at Water's Edge Mountain x13 Mystic Sanctuary Reliquary Tower Shivan Reef I really like this hybrid style between wizard tribal and spellslinger decks

Any time you could mulligan and this card is in your hand, you may exile all the cards from your hand, then draw that many cards