Herald of the Pantheon You need to play an enchantress deck for Herald of the Pantheon to work, but theres a heavy overlap between enchantments and lifegain thanks to cards like Sigarda's Splendor and Trudge Garden, plus this green creature offers great ramp via cost reduction
2 Leonardo, Sewer Samurai Creature Falling just short of the top spot is Leonardo, Sewer Samurai, mainly because its sneak cost is virtually the same as its base cost

Abbot of Keral Keep Act on Impulse Alania's Pathmaker Anep, Vizier of Hazoret Archaic's Agony Ardent Dustspeaker Asgardian Inspiration Atsushi, the Blazing Sky Blazing Crescendo Bonehoard Dracosaur Brazen Cannonade Breeches, Eager Pillager Breya's Apprentice Burning Curiosity Cait Sith, Fortune Teller Capricious Sliver Case of the Burning Masks Caves of Chaos Adventurer Chandra, Fire Artisan Chandra, Flameshaper Chandra, Heart of Fire Chandra, Legacy of Fire Chandra, Pyromaster Chaos Channeler Charred Foyer // Warped Space Chase Stein, Runaway Cleon, Merry Champion Clockwork Percussionist Commune with Lava Count on Luck Crimson Caravaneer Crimson Operative Crossover Collaboration Daredevil, Fearless Fighter Dark-Dweller Oracle Diversion Specialist Duchess, Wayward Tavernkeep Ecstatic Beauty Electrostatic Blast Emberheart Challenger Embodiment of Flame Embrace the Unknown End-Blaze Epiphany Endrider Spikespitter Equilibrium Adept Evendo Brushrazer Experimental Synthesizer Fateful Tempest Feldon, Ronom Excavator Fire Giant's Fury Fire-Brained Scheme Fires of Mount Doom Flameskull Galvanic Relay Geistflame Reservoir Gila Courser Glimpse the Impossible Goblin Researcher Grotag Night-Runner Harnesser of Storms Harnfel, Horn of Bounty Haste Magic Headliner Scarlett Hedron Detonator Heroes for Hire Heroes' Hangout Ignite the Future Impossible Inferno Inspired Tinkering Inti, Seneschal of the Sun Irascible Wolverine

2 - Portgas D
You don't need a bunch of ramp