An extra copy of Aurora Dreaming Guardian allows us to better protect our top end threats with ward and having 2 copies of Grab Your Sword will really help by time against the fast lore decks such as the Amber / Amethyst one above
With lifelink built in, she can start growing immediately,every time you gain life, Aerith picks up a +1/+1 counter
Page 3 of the rulebook tells each player exactly what cards they should have in that first starting hand
Most decks wont have maindeck outs to something like The Tabernacle at Pendrell Vale, Chalice of the Void or Blood Moon
DISAPPEAR: When you play this character, you have the option to return a chosen character to its players hand
Theres card draw and pressure, but more importantly, Yshtola works as a powerful value engine once you stack it with auras like Curiosity and Sigil of Sleep