I doubt you'd need more than one or two in scenarios where they're showing up as random critters (they don't show up on the table much) but their "Graveyard" scenario sort of calls for one per player, with a small chance that some might never show up (they appear the first time each player rolls a 5 or less for initiative).
I've been using Reaper's Avatar of Strength for the one I've got, although my paint job's not quite up to the catalog version: