First wave allocations are limited
The infographic below by GoHub further explains friendship level bonuses
Any card with abilities which let you reuse it from the graveyard (encore, escape, flashback, unearth etc.) can make great discard fodder

1 2 3 4 5 6 7 A ------------- B ------------- C ------------- D ------------- E ------------- F ------------- G ------------- Go to these districts for the appropriate card: Dust Tornado (Mai, E7) Carat Idol (Yugi, D1) Shape Snatch (Bakura, A7) Rigras Leever (Joey, E7) Time Eater (Mako, E6) Servant of Catabolism (Tea, E5) Dharma Cannon (Grandpa, C4) Eternal Rest (Necromancer, A1) Eradicating Aerosol (Weevil, D7) Cold Wave (Rex Raptor, A7) Exile of the Wicked (Panik/Darkness Ruler, B6) Jowls of Demise (Isthar, D4) Novox Prayer (Tristan, D5) Electromagnetic Bagworm (Pegasus, A4) Strain Storm (Bandit Keith, C4) Souleater (Shadi, D4) Catapult Turtle (Labyrinth Ruler, A7) Warrior Elimination (King, B4) Moisture Creature (Kaiba, D4) Unlock Reincarnate By surrendering five times or getting five wins, you will be able to reincarnate a card in your chest to allow you to build your deck

However, for an "aristocrats" deck that relies on death triggers, such an ability is actually an upside, and is granted to a player's commander alongside ward, +3/+3, flying, and deathtouch