Melania is apparently just hard to kill because of the fungal infection her bloom is probably based on.

There are lots of mushrooms in Elden Ring Runes. I'm not just referring to the item, that exists throughout the Lands Between. There's lots of mushroom imagery throughout the game, but perhaps none so much because of the Goddess of Rot herself, Melania.

Malenia's bloom seems to be modeled following a specific type of fungus called Gymnosporangium juniperi-virginianae, or even more commonly, Cedar Apple Rush. This fungal infection parasitizes cedar and apple trees with reddish "flowers" that are actually spore-releasing galls. The spores then infect leaves, which could spread toward the whole tree, killing it. As noted by Reddit user Marshmellow_Bot, Cedar Apple Rush looks almost the same as Melania's rot bloom in Elden Ring.

And much like Malenia, killing Cedar Apple Rush can be just like hard. More than one Reddit user agreed that treating infected trees could be difficult, and when not done promptly, can ruin entire orchards.

But Elden Ring's mushroom theme goes way beyond Melania. YouTuber Ziostorm noted there are way more mushroom analogs contained in Elden Ring. He noted that not only does Melania's Bloom seem like Cedar Apple Rush, but the Twin Fingers resemble another fungal species called Dead Man's Fingers. The Erdtree appears like a giant Chantrelle mushroom, Godwyn's corpse appears like an Oyster mushroom, Ranni appears like an Indigo Milk Cap mushroom, and also the starry "sky" of Nokron, Eternal City might be explained away through the bioluminescent spores of the particularly colorful types of slime mold.

Ziostorm went, even more, to explain that Elden Ring might be explained as a huge turf war between mushrooms. Various in-game items confirm the Erdtree and also the Elden Beast found their way to the Lands Between from outer space, and in the Golden Amber item description, he posits the Erdtree didn't sprout from the seed but from the fungal spore. It then spread over the Lands Between, infecting my way through a mycelial network that drew in corpses from burial grounds to sustain itself.

Mushrooms are occasionally called "envoys from the trees" as this mycelial network allows trees to speak, sharing information with an intricate root system. This would also explain why the Two Fingers and Three Fingers are known as "envoys" for their respective gods.

There's more, but you will need to watch Ziostorm's video for the rest. Just don't be surprised when mushrooms come in even greater abundance when Elden Ring's Shadow from the Erdtree DLC arrives.

Most people consider Malenia to become elden ring Rune's hardest boss, although not everyone. There's a minimum of one player that's got so good at killing Melania, they are able to do it in only over 10 seconds.