To fill up your graveyard, Celes, Rune Knight and Mog, Moogle Warrior arrive with potent effects that get creatures into your graveyard, with the Celes also being her own wincon and value engine with her ability to grow your whole board every time a creature enters from your graveyard
Reducing Auron's power below the exiled creature's power won't cause the exiled creature to return to the battlefield
Character cards have some extra elements to them too: A character can have different variants (which means a character can ignore a deck card limit, but their forms cant) which can shift between each other for a reduced fee
General Leo Cristophe* If Leo cost a bit less mana hed be much higher up on this list, as at 5 mana returning one cheap creature, and growing based on how many creatures you have is just not that good especially given he lacks any protection or evasion
Personally, though, I've long wanted to build a mountains-matter mono-red deck with cards like Koth, Fire of Resistance, but there aren't really enough relevant cards to make it work