"I suppose the name is ambiguous. Mountain ash is a kind of tree. I typically create the circles from a powdered form, but this building is made of it, as are some of the boxes here that store magical objects."

"...I can boost plants' growth by singing to them. Maybe. Very maybe maybe. This was when I was like fourteen and thought it was cool, no practical application 'till now."

"...There is one tree it might be either very dangerous or very beneficial to boost. Maybe both. I don't know that I advise starting there, but it's a possibility if your magic can do that."

"I take it it's mystically important in some way, what tree is this?"

"It's just a stump now, but it was once a large tree, part of a grove of trees known as the Nemeton. A place of powerful magic, the tree stump is all that's left, and...it would be something if it was back, but I'd have to think long and hard on whether it would be worth it."

"You're the expert." For all her casual tone, there's absolutely no uncertainty in her voice.

"For now, I'll walk you through making a circle. Stiles already knows how, and Scott can't, so I'll let them entertain themselves."

They wait in the lobby.

Rapt attention again.

He retrieves a jar of dark powder from his stores.

"This is powdered mountain ash. The trick to forming a circle is achieving a state of mental tranquility. You have to be neutral to close a circle properly. Quieting the mind is difficult; Stiles was only able to do it once, as far as I know." 

He places the jar on the table.

"Grab a handful, and start walking around the area you want to protect. Make it small for now, this is just to find out if you can achieve the mindset." 

"Just on the floor okay?

Clear and tranquil mind, huh? She does try.

She's not very good at it.

"You don't have to try to clear all your thoughts, but as you walk, you have to walk with no intent other than to keep pouring the powder. Don't think about completing the circle, or creating a barrier. Just keep pouring."

"I see."

She does that, in a small floor circle, pourpourpour.

Her usual mindset is really not conducive to this sort of thing. She slips up the single intent at least once.

The circle fails to take shape.

"This isn't the only simple kind of magic, there are others that rely less on mindset. Let's take a look at some useful herbs that might not exist- or not have the same properties, in a world with different magic."

She sweeps up the ash with a little breeze. "Is it reusable?"

"That's why the powdered version is so useful, yes. Carving buildings and boxes out of it has its own applications."

He scoops the powder back into the jar, and procures another one.

"Wolfsbane is good to carry for anyone who'll need to face werewolves and their rarer cousins. It's not very friendly, so save it for defensive triggers, which will only affect those that instigate."

"It'll have a more visceral impact than some kind of strange magic from me, you think?"

"Certainly more targeted. Unfamiliar magic will work as a good offensive strategy, but not as a good defense. You'll make too many enemies that way." 

"Even if I only use it on instigators and no preemptively?"

"We can discuss how to convince people that's what you're doing. Foreign magic will look threatening to most in the supernatural world."

"I see. None of my magic except against a clear and present threat then."

"You'll have to use your own judgment in the end, but that's my recommendation. There's other techniques I could show you, but with a higher time commitment than you need to make, given your own magic. I'll give you these notes, and you can come back with questions as they come up."

"I'll definitely prepare some wolfsbane, I do know the importance of prep time. Something like thirty hours of work per Witch goes into twenty minutes of combat against Neuroi. Does that mean this group lesson is over?"

"For now. I have to get back to work." 

Students return to school, because spring break can't last forever.