Yolas is technically not a spell.

It's a sixth sense built into all Wolfblood's,  whereby they touch the ground and close their eyes.

Once with the eyes closed the Wolfblood's can then Concentrate on their surroundings feeling everything around them from tree's and animals near by, to friends or foe lurking in the shadow's Con check d10 - 2d6 +5

For this reason all Wolfblood's are expert trackers.