Elspeth can come down in the mid-game since she costs five mana, either establishing a board presence with her first two abilities or destroying a problematic creature of your opponents, making her a control players dream planeswalker
Ultimately I like having Nahiri as my casual Equipment deck, as the variance in her ability makes every game unique, and like I get to play with Nahiri
Sleeve the Whole Collection, Not Just the Good Cards We get asked this constantly
Second, this makes enchantments and artifacts creatures
God help you if the cards you milled have flashback or if your opponent plays any form of graveyard recovery
More recently another version of the mechanic has come out with the new Doctor Who Universes Beyond set with the 'Doctor's Companion' mechanic, which allows cards with the mechanic to be paired with any Time Lord card in the command zone