While a day of preparation might result in slightly stronger protective spells, it would also result in a very cold trail. As such, it's a little under an hour later when Kailyn sets out, with Gregor, Vorel, and Epsilon following invisibly overhead.
The trail leads almost straight east, and it quickly becomes clear that these raptors were relying on magical means of avoiding being tracked; they put no effort into hiding their trail by conventional means. The path does, in fact, go through one of the larger lakes in the area - but Kailyn is easily able to pick it up again on the far side.
There are no notable encounters* until you're about four-fifths of the way to the edge of the swamp. And then Kailyn staggers under an invisible assault; huge gashes appearing in his sides from the claws of two raptors.
Of the raptors themselves, there is no sign - until Epsilon covers the area in illusory magical flame, revealing the distinct outlines of four velociraptors surrounding Kailyn - from the looks of it, all four of them attacked, but only two managed to penetrate the unicorn's armor - and those two nearly killed him on their own.
* There are three attacks from normal packs of velociraptors, and one from a giant land squid, but nothing that Kailyn couldn't have handled on his own.