Both War of the Spark and March of the Machine were the culmination years years-long Magic the Gathering story arcs with an explosive set featuring multiple worlds and a plethora of new, exciting cards. Both sets were also plagued with some controversy in terms of their storytelling and the cards released in the set.
Source:https://www.cbr.com/mtg-war-of-the-spark-march-of-machines-retrospective/