OoC: It's a simple matter of them taking double moves to Zaeryl's single move. They came at him from different sides and never completely converged into the range of a single cone. No matter how Zaeryl moves, if they stand right where they are, he'll never catch them both in a single blast.
And no, I didn't plan it that way. They have their agenda and Zaeryl has his, and it just all fell together that way.
One strategy might be for Zaeryl to "allow" them to herd him back to the group and hope they cluster together. But they way they've been moving, it should be obvious to him that there's no guarantee of that.
Really, it's a matter of herding one person with only two people. If they spread out just far enough but not too far, they can prevent him from moving in any one direction, but they really can't control which other direction he picks. If they spread out too far or bunch too close together, they can't even do that.
And no, I didn't plan it that way. They have their agenda and Zaeryl has his, and it just all fell together that way.
One strategy might be for Zaeryl to "allow" them to herd him back to the group and hope they cluster together. But they way they've been moving, it should be obvious to him that there's no guarantee of that.
Really, it's a matter of herding one person with only two people. If they spread out just far enough but not too far, they can prevent him from moving in any one direction, but they really can't control which other direction he picks. If they spread out too far or bunch too close together, they can't even do that.