Heliod is one of the best tools for a white lifegain deck to have ever been printed, as for just one generic and one white it can give a creature lifelink
Playing mono blue means you wont have to worry about fiddling with mana
This is on par with, though slightly worse than, the others of the wave of semi-playable 3 cost mana rocks, like Cursed Mirror and Midnight Clock
Beast Within Beast Within Bringer of the Green Dawn Druid of Horns Elder Gargaroth Fresh Meat Garruk Wildspeaker Garruk, Primal Hunter Garruk, Unleashed Herd Migration Lukka, Bound to Ruin Primeval Bounty Pulse of the Tangle Radagast, Wizard of Wilds Savage Conception Sawtusk Demolisher Somberwald Beastmaster Soul of Zendikar The Huntsman's Redemption Thragtusk Trumpeting Gnarr Viral Spawning Vivien, Monsters' Advocate
He trades raw power for positioning and rewards precise timing