I'm fairly certain it has to be face-up for its effect to activate. Just wondering, but why would you put it face down in the first place, may I ask? Are you afraid they might activate the all-powerful Eatgaboon?
Where is this card now? First I spend overs 35,000 keys farming Harpie Hunting Ground for nothing!!,So I give up. then I just start to build Kaibaman Deck but this card keeping disappear for a weeks while I grabbed enough of money. FU! duel link.
I bought two from Card Trader. Harpie Hunting Ground is not that powered, I spent some days to farm it and after dueling sometimes with it I found out that the spell removal is a bit dumb, if you summon an Harpie and your opponent has no spell or trap cards on the field you are required to remove one of your own, including Harpies Hunting Ground.
I've watched the AI Auto duel with my Kaibaman deck and play it in defence position even though i have a BEWD in myhand. The AI doesn't know how to use a lot of cards effectively which i forgive but that is the only use of a kaibaman card.
It's like LOOKING IN THE MIRROR!! HERE COMES KAIBAMAN!!!
best card ever. Singlehandedly makes cards like white effigy (too weak. Still needs to survive to allow tribute to blue eyes next turn possible), flute of summoning dragon (needs lord of D - a weak ass monster and flute of summoning dragon all together + blue eyes for it to work) and paladin of white dragon (ritual monster + ritual spell card + possible option of sonic bird + senju = what a waste of space), all completely inferior compared to this.