ABANDONED. Comtemporary fantasy, possibly YA novel, guy discovers magic is returning to the world and a subterranean magical, dark all-consuming evil is returning with it

[Aaron]

It was definitely contemporary fantasy. Might have been YA. Main character may have been a biker, or liked motorcycles. I remember there being scenes of him riding in a desert/barren mountains possibly?
It is revealed to him magic is returning to the world, he's a wizard, and there's a "tide of darkness" - a semi-sentient race of magical creatures made of or somehow part of the darkness, specifically - welling up underground threatening to consume the world that is linked to the magic level of the world.
Details are foggy but that's what I remember.
I read this more than a decade ago for sure. Cannot for the life of me remember the name of the book or the author.

[Etta.n]

Was this in a trilogy, or at least had a sequel, where he's a Merlin-foil type character with manic/depressive moodswings, and he finds some graduate students (maybe a love triangle) who are trying to cure a plague (that's maybe turning people blue before it kills or corrupts them)?

[Aaron]

Hm, does not ring a bell, but definitely part of a series, because I remember getting to the end and then not being able to find the second book at the library.

[Lobstergirl, au gratin]

Aaron, are you still looking or did you find this?

[Kris]

No response, moving to Abandoned folder.

Aaron (OP) was last active on the site in December 2018.