Eolas is an extrasensory ability used mostly by wild wolfbloods that allows them to discover a person's whereabouts by connecting to nature. Although it can be addictive, some wolfbloods are able to control it. This power, according to Maddy's mother, can cause family separations and disputes.
The word comes from the Irish Gaelic eolas, meaning 'knowledge of direction' or 'guidance'.
To use Eolas, a Wolfblood must feel what is all around them- the wind around them, the ground beneath their feet. They can then use Eolas to show them something that is happening elsewhere, for instance, if you were in the middle of the woods, you would be able to see into the school. Using Eolas can also improve your reflexes, as shown by Rhydian when he is blindfolded and turned around to knock a can off of Liam's head.
Although Maddy got addicted to it in Series 1, she is seen using it in recurring occasions during Series 2 but seems to have no addictive effect on her.