Just noticed it...by killing an escort when that 25% triggered . I doubt it's intentional as it says 'nearby foes'
Edit: but thinking about how other area effects work, I realize this might be intended but I was just a bit...disappointed. Perhaps changing 'foes' to 'creatures' might avoid this kind of misunderstanding.
ToME online profile: http://te4.org/users/zonk
Addons (most likely obsolete): Wights, Trolls, Starting prodigy, Alternate save/resistance system