2) B2: Keep of the Borderlands. My copy came with my Moldvay Basic Set. Although, I practically consider it core rules.
3) Deities & Demigods, if that doesn't count as core. (I don't count it as core myself.) Otherwise, I guess its a tie between the World of Greyhawk & Lankhmar: City of Adventure. For WoG, I guess the box set since it has more content, but--nostalgically--the folio will always be the real WoG for me.
4) I played 2e, but only for a few years. I don't remember any of its supplements really standing out in my mind.
				
			3) Deities & Demigods, if that doesn't count as core. (I don't count it as core myself.) Otherwise, I guess its a tie between the World of Greyhawk & Lankhmar: City of Adventure. For WoG, I guess the box set since it has more content, but--nostalgically--the folio will always be the real WoG for me.
4) I played 2e, but only for a few years. I don't remember any of its supplements really standing out in my mind.
 
				 
 
		
 
 
		 
 
		 In that case, I will vote for X4 and X5 (they were two parts of an epic module).  Those two modules taught me how to design an "epic quest" campaign adventure.
   In that case, I will vote for X4 and X5 (they were two parts of an epic module).  Those two modules taught me how to design an "epic quest" campaign adventure. 
 
		 
 
		
 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		