I have to admit that playing Harpies' Hunting Ground in combination with Mind Scan has always been a dream of mine and I’m sure this idea crossed your mind as well if you were around back when this deck was still popular.
It can’t be denied that Blackstorm Rising has significantly improved this archetype by making the Field Spell available without the use of the homonymous Skill and by also giving us a card that can search it, but Harpies still seem to lack something when it comes to offense.
If you believe that pretty much any deck can reach King of Games right now with the help of some expensive backrow, you would be absolutely right: Harpies are by no means going to make a comeback because of this new wave of support, but this doesn’t mean they are not a viable deck; if you invested in this new Main BOX and you feel like going back in time, you might want to try out this deck.
This Field Spell will increase the ATK of your monsters by 200, putting all of them, with the exception of Harpie Dancer, above any Level 4 Destiny HERO and making the able, with the help of Mirror Wall, to survive even the attack of a Blue-Eyes White Dragon or a Cosmo Brain.
Whenever a monster named “Harpie Lady” or “Harpie Lady Sisters” is Normal of Special Summoned on either side of the field, the player who Summoned it targets and destroys a Spell/Trap Card on the field.
Since Harpie Lady 1, Harpie Queen, Harpie Dancer and Cyber Harpie Lady are all treated as “Harpie Lady” while on the field, you will be able to trigger the effect of the Field Spell quite often, but keep in mind that it is mandatory, so you might want to avoid activating Harpies’ Hunting Ground right away when you are going first or there aren’t any suitable targets on the opponent’s side of the field.
Harpies became notorious in Duel Links for their ability to blow up the opponent’s backrow, but not all decks run a lot of Spell/Trap Cards right now.
You can discard Harpie Queen from your hand to add a copy of Harpies' Hunting Ground from your Deck to your hand; Harpie Queen has a pretty high ATK for a Level 4 monster, reaching 2100 ATK under the Field Spell.
Due to the fact that we are running 3 copies of this card, you might want to reduce Harpies’ Hunting Ground to only one: while removal for Spell/Trap Cards is not uncommon in the current meta, the deck can function without the Field Spell.
Harpie Dancer, in combination with the Field Spell, is able to destroy two Spell/Trap Cards per turn: its effect allows you to return any WIND monster you control to the hand and then Normal Summon one.
You can activate Harpie Dancer's effect even if you don't have any monsters in your hand and, since it's not stated otherwise, you can also return Harpie Dancer itself to the hand and then Normal Summon it with its own effect.
The fact that Birdface can’t trigger the effect of Harpies' Hunting Ground is not necessarily a bad thing: sometimes your opponent may simply not have anything you can or want to destroy. When this card is sent to the Graveyard, you can search Cyber Harpie Lady; now that Amazoness Onslaught is not around anymore, it will certainly be easier to activate this effect, but keep in mind that it can miss the timing.
Another new card that comes from the latest Main BOX, Hysteric Party gives Harpies the ability to swarm the field very quickly.
You need to discard a card in order to activate this Continuous Trap and you must also have at least a monster named “Harpie Lady” in the Graveyard first, but that’s pretty easy thanks to Harpie Queen.
The monsters Special Summoned by Hysteric Party are destroyed when it leaves the field, but you could Tribute one of them to activate Enemy Controller and steal an opponent’s monster without repercussions.
Widespread Ruin is a really powerful card, it allows you to destroy the Attack Position monster your opponent controls with the highest ATK, meaning that trying to play around it by attacking with the low ATK monsters first will not work; this Trap Card works very well against Masked HEROes.
Mind Scan From the third turn and onward, you can see the opponents card as long as your Life Points are 3000 or Higher.
You might be tempted to run Harpies' Last Will, but the Skill is not that easy to activate due to its requirements and it also doesn't solve any of the issues the deck has. Mind Scan is a pretty obvious choice: it allows you to know what cards you want to destroy and which ones you can play instead just play around.
When it comes to their ATK, Harpies are really unimpressive, especially when you compare them to some of the most common monsters in the current meta, they will struggle dealing with Blue-Eyes, Masked HERO and Vampire, but they do have a good matchup against Gladiator.
Sheer ATK is not everything, but the deck also lacks removal: Wild Tornado and Big Bang Shot are interesting options, but they are too slow for modern standards.
I wouldn’t advise investing in Blackstorm Rising specifically for Harpies, it should be more of an incidental thing; Bujin and Dragunity look very promising and, if they become popular, they will just be other decks against which Harpies can do very little.
Not sure why you'd include TTH in a deck with so many other traps. It's not worth hoping to draw it first compared to how likely it'll be a dead draw. Especially if it's taking up the slot a second ECon would have.