|“|| "This is some of what you'll use to create the barrier. This part is for you, Stiles-- only you. [...] It's from the Mountain Ash tree, which is believed by many cultures to protect against the supernatural. This office is lined with ash wood, making it difficult for someone like Scott to give me any trouble."|
"Okay, so then what? I just spread this around the whole building and then either Jackson or whoever's controlling him can't cross it?"
"They'll be trapped."
In Teen Wolf, Mountain Ash, also known as Sorbus americana, is a form of ash created by burning the wood from a Mountain Ash tree, which possesses the ability to protect against the supernatural by preventing them from coming into contact with it. It was first introduced in Season 1, when it was revealed that the Druid Emissary Alan Deaton had lined his entire animal clinic with both the wood and the ash to prevent any supernatural clients from doing harm inside, and it has played a significant role in the series ever since. In real world mythology, the wood is often referred to as Rowan and supposedly has the ability to scare off evil beings. In addition to the animal clinic, Eichen House, the McCall House, and the boathouse in the Martin family lake house are all lined with Mountain Ash as well; the former prevents its supernatural inmates from escaping, whereas the latter two are to protect those inside the house from supernatural threats, particularly those who are human.
Its typically used by Druids to not only ward a space against supernatural creatures or create a trap to capture them, but can seemingly also modify behavior as well, according to Alan Deaton; this may explain how he protected himself from Peter Hale's attack on him in Code Breaker and how he forced Kali to shift back into human form in Frayed.
Mountain Ash seems to be mystically drawn to itself, allowing any human (including those who utilize supernatural forces such as Druids and Banshees) or unnatural creature (such as Chimeras) to create perfectly formed barriers by throwing the ash into the air; Melissa McCall and Lydia Martin each completed barriers in the McCall House and Martin Lake House, respectively, when they threw the ash and allowed it to fill the gaps in their already-lined homes, while both Marin Morrell and Jennifer Blake created perfect circles of Mountain Ash around them by willing it in a circle and throwing the ash in the air.When used correctly, Mountain Ash can form a almost impenetrable barrier that no supernatural creature
In Lunar Ellipse, at the old distillery, the potential True Alpha Scott McCall was able to forcibly dispel the barrier set up by Jennifer using sheer willpower, a feat believed to be impossible; Scott himself has implied that the rush of power from becoming an Alpha from sheer force of will combined with the relatively thin barrier of ash and the life-or-death situation he was in allowed him to do this, and he has yet to replicate this feat since. Another example is Jordan Parrish, who is possessed by the Hellhound, Cerberus, and whose flames are powerful enough to literally burn the mystical aspect of Mountain Ash out of the barriers. In addition to these examples, the Oni have demonstrated an ability to break through Mountain Ash barriers, though it takes time for them to find weak spots that they can exploit, and the Ghost Riders can bypass the effects of Mountain Ash by teleporting in and out of the barriers.
Strangely enough, Mountain Ash has been shown to have no effect on Chimeras due to their non-supernatural status. They can cross it, hold it, and use it with absolutely no problem, just as normal humans can. In Dreamcatchers, Tracy Stewart, a Werewolf-Kanima Chimera, was able to cross it as if it wasn't even there. Later on, the Werewolf-Werecoyote Chimera, Theo Raeken, was able to hold it and then use it against Scott McCall. Banshees are another being with supernatural powers who can wield Mountain Ash like any other human, as Banshees are technically just human women who channel supernatural forces and use them without being controlled by them as shapeshifters are.
Uses of Mountain Ash
- Mixing Mountain Ash with Wolfsbane and adding it to steel that was forged with Marie-Jeanne Valet's blood under a Full Moon to create Marie-Jeanne's Pike. ("Maid of Gévaudan")
- Fortifying the defenses of Alan Deaton's animal clinic. ("Code Breaker")
- Stiles Stilinski creating a trap at the rave in order to capture Jackson Whittemore and learn who was controlling him.
- Scott McCall and Alan Deaton creating Mountain Ash pills and swapping them out with Gerard Argent's cancer medications to prevent him from achieving his goal of becoming a Werewolf. ("Fury"), ("Master Plan")
- Marin Morrell creating a barrier inside First National Bank's vault to force Scott McCall and Derek Hale to fight the rabid Vernon Boyd and Cora Hale. ("Chaos Rising")
- The Darach using Mountain Ash to create a barrier to prevent anyone from reaching Alan Deaton, her intended "healer" sacrifice. ("Currents")
- Marin Morrell creating a barrier to prevent herself from being harmed by Deucalion, Kali, Ethan and Aiden. ("Alpha Pact")
- Jennifer Blake creating a ring of Mountain Ash to protect her from Scott McCall, Derek Hale, and Deucalion. ("Lunar Ellipse")
- The Calavera Family hiding the Triskelion Urn in a box made of rowan wood and filled with Mountain Ash to prevent Derek Hale and Peter Hale from getting inside of it. ("More Bad Than Good"
- Melissa McCall creating a barrier at the McCall House to prevent the Oni from coming in and attacking herself, Rafael McCall, Scott McCall, Derek Hale, Kira Yukimura, and the twins. ("Galvanize")
- The barrier also confirmed Kira's status as a supernatural Thunder Kitsune when she was unable to cross it.
- The Chemist creating a barrier to trap the Werewolf test subject who was exposed to and killed by the Modified Canine Distemper Virus. ("Weaponized")
- Alan Deaton making a barrier in the Beacon Hills Animal Clinic to prevent Tracy Stewart from leaving (though it was ultimately unsuccessful thanks to her Chimera nature.
- Theo Raeken making a barrier in Beacon Hills High School to trap Scott McCall and Liam Dunbar with the intention of having Liam kill Scott. ("Status Asthmaticus")
- Melissa McCall and Braeden creating barriers at the McCall House to protect Malia Tate from her mother, Corinne. ("The Beast of Beacon Hills"), ("Apotheosis")
- Mason Hewitt and Corey Bryant creating a barrier of Mountain Ash to prevent the Ghost Riders from coming to capture and erase Gwen from reality. ("Sundowning")
- In large and potent quantities, Mountain Ash can even weaken a supernatural creature who is in its presence, as Scott McCall and Kira Yukimura both stated that standing outside of the heavily-fortified supernatural ward of Eichen House was making them feel weak and sedated.
- Mountain ash has no effect on humans, Banshees, or Chimeras.
- Malia Tate referred to her first experience with mountain ash as "weird."