A permanent that’s both a Merfolk and a Faerie is counted only once when determining X.
2007-10-01
The value of X is determined when Silvergill Douser’s ability resolves. It won’t change later, even if the number of Merfolk and/or Faeries you control changes.
: Target creature gets -X/-0 until end of turn, where X is the number of Merfolk and/or Faeries you control.
: Target creature gets -X/-0 until end of turn, where X is the number of