"We knew we wanted him to be the first four-ability mono-blue planeswalker
9 Second Harvest While Parallel Lives is arguably the single best card for token-heavy decks like Elf tribal decks, Second Harvest also has its uses
Death Tyant shines in combat, turning any creature death into 2/2 Zombie tokens
Returning to Sower being a creature you can get repeat uses through bounce spells, cast it at instant speed with things like Aether Vial and easily protect it with effects like Kira or Spellskite
As a long-time Esper player, primarily in Standard, I've always focused on the Control strategies of Esper - building decks that seeked to slowly dismantle my opponents, only to eventually outpower them in terms of resources
Mortuary Mire, Witch's Cottage, and Haunted Crossroads can be part of game-winning sacrifice engines, and putting such easy recursion on a land just asks for trouble