[considering for a long beat. He's not an idiot, he knows how dangerous that sounds. But still.]
I get it. But if there's even a chance then I want to help, and I know Saber will too. Maybe it's not as useless as it sounds. I can make vacuums too, and create my own air. I'm not really sure about the dream thing, but...
[He shrugs, but it's far from casual. Serious battles are nothing to take lightly] Well, astral magic is pretty versatile and maybe it could counter some of that stuff. There's spells we can use that will hit creatures even in other dimensions, so maybe he can't intangible his way around them. And Saber's nearly immune to anything I throw at her, so maybe she has a resistance to this Dark Matter.
It's hard to explain, but you never know unless you try.
[And then a tiny smile] Maybe once I get to fight you, it'll make more sense.