Springjack Pasture looks like the more reliable engine, but Springjack Shepherd wins for flavor and mechanical evolutionary history

Accursed Duneyard Asceticism Baron Sengir Black Poplar Shaman Boneknitter Broken Fall Clockwork Gnomes Crypt Sliver Dark Dabbling Daru Mender Dawn Charm Death Ward Debt of Loyalty Delif's Cube Draconian Cylix Elephant Graveyard Fanatical Devotion Gaze of the Gorgon Goblin Chirurgeon Heal the Scars Herbal Poultice Horizon Seed Horror of Horrors Isao, Enlightened Bushi Jhoira's Toolbox Krosan Warchief Lim-Dl the Necromancer Loxodon Hierarch Avatar Loxodon Mender Medicine Bag Mending Touch Metallurgeon Molting Skin Niall Silvain Orcish Healer Poultice Sliver Pteron Ghost Ragnar Refresh Regenerate Regeneration Reknit Rushwood Herbalist Savage Thallid Seedling Charm Soldevi Sentry Sporeback Troll Suture Spirit Swarmyard Tel-Jilad Lifebreather The Brute Trolls of Tel-Jilad Vagrant Plowbeasts Vigilant Martyr Village Elder Vital Splicer Vitality Charm Welding Jar Xantcha Yavimaya Hollow

Other popular damage doublers include Furnace of Rath, Dictate of the Twin Gods, Fiendish Duo, and Fiery Emancipation/City on Fire as damage triplers
Infernal Reckoning $3.99 I have no idea how effective Infernal Reckoning will actually prove as a tournament level hate card, but the fact that I havent heard much chatter about it tells me that its probably not good enough to make an immediate impact
And with each deck containing 50 new-to- Magic cards, there's plenty of fun to be had
That's why Y'shtola is the best