Grail Mud Consumption

There was a mass of twisted magical energy called “mud.”
Francesca extracted it from the Greater Grail in Fuyuki at the same time she stole a portion of the Grail’s “substance.”
Faldeus, who had inherited memories of the third War, recognized its nature. Before that, the Grail had been absolutely clear, unpolluted by that clump of sentient magical energy.
Faldeus, following his memories, had immediately realized its identity. He had immediately proposed the “mud” be quarantined.
No orders, however, had come down for its isolation, disposal, or purification. His superiors and their collaborators had an interest in the muck — in the “human evil” that had polluted the Holy Grail and its power and which still retained the power to defile a new grail seventy years later.
...
All of the muck’s hosts had been seized by madness. It had ultimately consumed their bodies as well. Bazdilot, however, remained just as he had been before accepting it into his body. In fact, he was apparently nurturing the mud on his own magical energy, increasing its volume. The Scladio Family praised this as proof of Bazdilot’s power as a mage, claiming that he had subjected himself to his own magical domination in order to control the mud while preserving his sanity.
Faldeus knew better.
It was true that Bazdilot was employing his own magecraft in order to control and cultivate the muck. He must also be maintaining an extraordinary effort to prevent it from dominating his mind. Nevertheless, Faldeus was aware that there was a single mistake in the Scladio Family’s accolades.
Bazdilot was not controlling the mud while preserving his sanity; the man called Bazdilot had been mad long before becoming its host — possibly from the very beginning.

-F/sf Vol 3

Alkeides, for his part, drew his bow back especially far.
The longbow bent back. Just as it seemed about to snap in two, it was released... and “it” took form in the sky above the church.
It were nine arrows shrouded in ominous magical energy whose twisting trajectories looked like titanic serpents.
They covered the sky over Main Street like the Hydra of legend, devouring not only the onrushing Noble Phantasms, but flame, cold, and even lightning alike.

-F/sf Vol 5