Zyra's new origins are pretty interesting. In it, an area around the southern parts of the Kumungu Jungle were ravaged by voracious carnivorous plants. However, an ambitious sorceress in the Rune Wars was seeking something there, and fought the plants with her escorting army of soldiers. During that fight, a 'rogue spark' ignited the gases of the swamps and basically made the surrounding area explode, killing every living thing in the vicinity. Zyra eventually emerges, a creature that is a fusion of the sorceress's runic magic and the carnivorous plants.
Now about that explosion...is it possible that *That* is the Kumungu Affair that Ivern mentions? For one, Ivern is listed as one of Zyra's related Champions. Along with that, Ivern seems to hint that Bramblebacks (Red Buff) are native to the jungles (they are, after all, living plant creatures). He even jokingly states that he thinks it was Brambleback's fault. Now why would he blame Brambleback? I believe it's because Red Buff is specifically associated with fire, which can very well have been the 'rogue spark' that ignited the swamps and blew up the Garden of Zyr. However, we know now that it may have been the sorceress's runic magic that ignited the spark.