Diablo 2

There are partial truths in what both the prior people have said, here is the whole truth. Wirts leg and a tome of portal put into the cube in Act One will make a cow portal IF you have beaten Diablo in that 'kind' (Norm, Nightmare, Hell) of game AND you or a member of the people your are in party with have not killed the cow king in a prior cow game in that 'kind' of game. EXAMPLE: You kill diablo in norm...you go get wirts leg. Your return to the rogue camp and put leg and a tome of portal into cube...moph it...you get cow portal. Your char can makke a cow portal until it kills or one of it's party kill the king. Once you have killed the king or have been in party with someone who does, you can no longer make a cow protal in norm. This DOES NOT mean you can not go into a norm cow game...only that you cannot make it ever again with that char.
Are we clear?

for the secret cow lev u dont transmutate a scroll of id. instead u transmutate wirts leg adn a scroll of town portal, also u dont have to beat all the difficulties u just have to be around lev 45ish. Also if u want to do the lev again dont kill the cow king. if u do u wont be able to do the cow lev ever again. so if u have battlenet make sure to kill every cow except 4 the cowking. then just start a new game and do it again. also is\f u are playing with more than one person tall ur party members to get out of ur party befor they kill the cowking that way u can dothe lev again and get the items thte cowking loot. make sure to have a high magic find rate it really great cause there are like a thousand cows to kill.