Viral God Slayer Magic

Viral God Slayer Magic (病の滅神魔法, Byō no Metsujin Mahō) is a Caster Magic, Lost Magic, and — going by name and theme, an extremely deadly variation of God Slayer Magic, which allows its users to control malignant forms of bacteria in the surroundings; it's later known that it's one of the few forms of Dual Element God Slayer Magic in existence, created through the implantation of a poison-based God Slayer Lacrima and learning from an air-based God Slayer tome, both of which are of extreme rarity. Typically, through the use of elements, it's considered to be a highly-potent form of Elemental Magic.

It's current and only user is Daemon Mastema, being his current signature magic; he acquired the magic through unknown means, with his reason for its usage to match his elder sister and guild master, Marta Rayhunton, in terms of power and wanting to become a fellow Slayer to feel much closer to her.

Overview
"Do you feel it? Your body getting weaker and weaker, I mean. Of course you do. It's because of the malignant bacteria that's entering your system. In a matter of moments, you will be reduced to nothing — your vessel ravaged by the myriad viruses eating you from the inside-out."

- Daemon Mastema cryptically explaining the mechanics of his powers to a now-dying opponent.

Trivia

 * Permission has been granted by Per.
 * Most of the abilities here are based on the effects of various bacteria existing in the environment; to an extent, they're also based on the life-giving powers of Zagan — one of Solomon's seventy-two Djinn from the anime/manga series, Magi: The Kingdom of Magic.
 * Originally, this was set to be one of Daemon's magic back when he was first created. However, the idea was later scrapped because of various reasons, one which was that it didn't sound sensible at the time. Now, with Per's help, the author finally found some grounding for the article's functionality.