The deck used the obviously-undercosted effect of Survival of the Fittest to put powerful creatures directly into the graveyard, only to reanimate them with Recurring Nightmare
Magda, Brazen Outlaw in conjunction with Sorcerer Class is going to get up to some mana generating shenanigans, and once that happens, I see no reason why Sorcerer Class cant fuel storm-esque kills on otherwise stalled battlefields
The vast majority of bans in TCGs focus on stopping strategies that dont let opponents feel like they are getting a chance to play (mill, discard, and burn)
Thats more than just a fix, though
Dreadhorde Invasion, Battle for Bretagard, Felidar Retreat, Sigil of the Empty Throne and Anikthea, Hand of Erebos herself all help your board go wide, while cards like Miraris Wake, Boon of the Spirit Realm, and Heliod, God of the Sun can make them stronger