As a mage who's powerful enough to be considered a god, Solas will be a dangerous foe, especially given that 4's hero will likely be someone new, someone whom Solas has no bond, friendship, or romance with. Someone whom Solas knows will be a thorn in his side. But he's got a war to fight, and has to rely on other methods to get rid of you.
I imagine that while Solas won't fight you directly until the end, he might keep an eye on you and your party via scrying, which could lead to some interesting cut-scenes. And if he knows where you are just by looking into an orb, mirror, or bowl of water, he probably can also influence where you are. Like he sees you walk into a city, and he warn agents of his in the vacinity, or casts a spell to mind control people. Or what if he sees you entering a dungeon or forest, and conjures monsters for you to face? Or worse, as the most powerful dreamer ever, what if he can manipulate your dreams while you sleep?
What would you imagine the Dread Wolf would have up his sleeve?