You're missing the biggest advantage of Retreatman. You're using 2 resources to take care of his 6cc guy. If he casts it again, he would have wasted 12cc and by then you would have played enough allies, burn, control cards to either rush down the hero or take care of Oggloth
Edit: Retreatwas the main reason why Humans were rather hated in CotC. A 2cc card that is available to all humans that takes care of any ally, the higher the cost, the better
Bookmarks