The countdown text “x more” or “ready” on Yogg-Saron, Master of Fate counts spells countered by counterspell but the effect does not trigger if less than 10 spells actually cast.
cast 9 spells,
have your opponent cast counterspell,
cast one more spell.
Yogg-Saron, Master of Fate card says “ready” but when cast no battlecry effect happens.
Either card text does not update on countered spells or battlecry effect happens if 10 spells were cast, including countered spells