It depends on the job. If you're going for a job where the person reading it is likely to understand or have played WoW, then I'd say go for it - it's ballsy and shows you're a match for the company culture, and they'd recognise it as an achievement.
But if the person doesn't understand WoW, all they'll see is "WoW" and get a bunch of negative connotations in their head that will probably hinder you more than help. You could maybe consider saying you've demonstrated leadership in a team game and achieved global recognition for your team, then when asked in an interview you could give the specifics and be there to make sure it comes across in the right way, but it wouldn't be the easiest thing in the world to pull off. It depends how confidently you could do it, but then if you're asking this question, it makes me think you might need guidance for that, which makes me lean towards saying it's better not to mention.
Edit: Re-reading OP, I doubt you could get a lot of mileage out of it for PGCE/teaching.