You don't choose a target for Atraxa's Skitterfang's last ability at the time it triggers
Venser in the command zone means we can reliably use the most powerful proliferate engine available to us: Throne of Geth
Julius Jumblemorph Ixalan Vona, Butcher of Magan, Tishana, Voice of Thunder, Admiral Beckett Brass, Gishath, Suns Avatar Commander 2017 Nazahn, Revered Bladesmith, Inalla, Archmage Ritualist, Mirri, Weatherlight Duelist, O-Kagachi, Vengeful Kami, Mairsil, the Pretender, Taigam, Ojutai Master Razaketh, the Foulblooded, Zur, the Enchanter (Mummys Curse), Djeru, With Eyes Open, The Locust God, Karona, False God (All the Deserts), Nicol Bolas, Neheb, the Eternal Amonkhet Oketra the True, Temmet, Vizier of Naktamun, Atogatog (Cartouches & Trials), Hapatra, Vizier of Poisons, Samut, Voice of Dissent, Rhonas the Indomitable, Hazoret the Fervent Kaladesh Block Yahenni, Undying Partisan, Nicol Bolas, Child of Alara (Five-Color Energy), Rishkar, Peema Renegade, Kari Zev, Skyship Raider, Sram, Senior Edificer Commander 2016 Breya, Etherium Shaper, Atraxa, Praetors Voice, Tymna the Weaver // Ravos, Soultender Other Commander Decks Thada Adel, Acquisitor, The Ultimate Golgari Deck, Anafenza, the Foremost (shutting down shenanigans), Momir Vig, Simic Visionary (no green creatures), Kytheon, Hero of Akros (Tribal Gideon), Tasigur, the Golden Fang
Of those, his minus abilities pack a punch, considering you can use his -3 ability as soon as he is summoned
Additionally, Water Shuriken is a stackable ability, if the player has two Greninja on the field, they can distribute up to 40 damage per turn
