For too long, the consensus on handcuffs was that it was kind of slow and niche. Why cuff that cultist for two actions when you can just blow their head off with one? And what about all the scenarios without bi-brachial enemies? This upgrade, which makes the cuffs fast and cheap, answers that criticism somewhat, but then you hear complaints about the 2xp.
The truth is that Handcuffs aren't for the weird kinky decks. They're for the romantics out there. Too many guardians just want a series of quick flings with their enemies; no commitment. Handcuffs -- and these fast, doom-removing handcuffs especially -- let you invest in a long-term relationship. Rather than cuffing and ditching the enemy; you cuff and engage it, and then march it around the rest of the scenario with you. Of course, this approach has been noted before, including by @sonicknight15 in his review on this page, but with several new cards making the strategy even easier and more rewarding, an updated discussion of how to find love in the encounter deck, and what to do when you've found it, seems to be in order.
1) PUT YOURSELF OUT THERE
If you are running a cuff deck, you shouldn't just sit around waiting for the perfect humanoid enemy to drop down from the heavens -- or rise up from the abyss. You gotta show some initiative. The two best ways are with
a) On the Hunt: On the hunt is cheap, fast, and usually gets you what you want from the encounter deck, assuming there are at least 3-4 humanoid enemies in there. Importantly, it replaces your usual draw -- so that's one turn you don't have to worry about Rotting Remains or Frozen in Fear. If you're the type who knows EXACTLY what you want in a life-partner and won't settle for less, On the Hunt (3) is for you. As a plus, On the Hunt (3) guarantees you a handsome divorce settlement if the relationship goes south at some point...
b) Kicking the Hornet's Nest: Now the sparks are flying! Play this feisty event, and let that Brood of Yig wow you with an expensive dinner (3 resources) and amazing tales of the glory days of Valusia (a testless clue).
Importantly, both these cards spawn the enemy engaged with you -- very nice for aloof humanoids, as well as the ones that usually spawn at an empty location. Also, the text does not say you "draw" that enemy, so if it has a nasty revelation effect, it won't trigger. Neither will its concealed keyword, making these cards the only known way to get that shyest of all enemies, the Coterie Agent (A), onto the map.
Additional notes: both these cards are tactics, and thus attachable to Stick to the Plan -- which should probably be your first upgrade in this build if you have access. This means that if you find your cuffs in your opening hand, you can have that enemy stuck to you by the end of the first round in the case of Kicking the Hornet's Nest (fast play, Hornet's Nest, evade, engage), and the middle of the second round in the case of On the Hunt (fast play, evade, engage).
2) INVEST IN THE RELATIONSHIP:
So, the first date went well and you're ready to take the next step. Where do you go from here? So many possibilities!
a) Interrogate: If you want to get to know someone, you have to ask questions -- like "what music do you like?" and "where did you hide the bodies you sick bastard?" Interrogate works very nicely in this build, because you can play it whenever you like; you don't have to wait for a humanoid enemy to conveniently show up at a locations with clues, preferably a high shroud one. It also circumvents restrictions on investigating, like the "haunted" keyword or the text on the Orne Library. The downside is that you usually have to pass a difficult check -- most often a (4). But you can make it easier with Fine Clothes. Of future note, it seems likely that the upcoming Allessandra Zorzi, who, according to the press release, likes to "smooth-talk [her] way out of danger," will come with a suite of new parley cards, some of which may slot in nicely next to Interrogate/Fine Clothes.
b) Scene of the Crime: Are there places that are particularly meaningful to your partner? Spend time there together, and watch the relationship flourish! It could be a cozy cafe, or a secluded overlook, or the site of a foul ritual which has left the surrounding countryside desolate and corrupted; the important thing is that it matters to them, so it should matter to you -- and it will, to the tune of two testless clues on any location you manage to start your turn at, shroud be damned. As with Interrogate, no need to count on the encounter deck to send you an enemy at the perfect time.
c) Dream Diary: Madman edition. When you meet someone special, it's natural to want to put your best foot forward. But it's also important to be authentic, and what better way to do that than to explore the subconscious by swapping dreams? Roland: "I dreamed it was exam week and I'd forgotten to study! LOL" Wizard of the Order: I dreamed of abhorrent sacrifices to ghastly powers which slumber foully in fathomless abysses of time and space, and of a drooling, idiot god who slouches along the mad spaces between the stars. ROFL" Ravenous Ghoul: "I dreamed I ate you both. LOLOLOLOL." How sweet would it be to start every turn with a four- Essence of the Dream? Of course, only a few investigators can take both handcuffs and the upgraded Dream Diary, and some of them will have a tough time passing the initial fight check to attach the cuffs. But you may be able to pull the off the combo regardless (see item 3).
Due Diligence/Seek the Truth -- See the review by @sonicknight15 on this page.
Trench Knife: Just joking -- this card always has and always will suck, no matter how many enemies are engaged with you.
3) WHEN YOU LOVE SOMEONE LET THEM GO
What do you do when you learn that your significant other(worldly horror) has fallen for your best friend? Do you get jealous and vindictive; do you cut ties; do you cling on desperately? No, you show that true love is self sacrificing by letting that best friend engage them off you. There are several situations in which this makes sense. Maybe one member of your party is really leaning into a handcuff build, so you take a copy or two of the cuffs to increase the chances that they show up in somebody's opening hand. If so, you cuff the first humanoid who comes your way and leave it for your buddy to engage. Similarly, if you have a seeker who is running the Dream Diary, you let them scoop up the cuffed foe. But most of all, if Trish Scarborough is on the team, it should just be a rule that anyone on the team with guardian access must run handcuffs. When you see her sailing around the map scooping double clues every single turn, you'll realize the truth of Tennyson's immortal lines: "'Tis better to have cuffed and lost, / Than never to have cuffed at all."
Addendum: If you can't find your dang cuffs, you can still make parts of your build work with two substitutes: Bolas and Existential Riddle. The first will make for a rocky relationship to be sure -- you'll have to take an attack of opportunity every turn, or more than one if your first action isn't to move, so it's not sustainable. But if you are a nine-health investigator like Parallel Roland and you've bolassed a one-damage enemy, it might be ok for a bit, especially if you're also running pain-loving cards like Lesson Learned. Existential Riddle, meanwhile, makes the enemy permanently aloof. If it has the hunter trait, it will follow you around and you can count on it to be at your location if you don't get too far ahead of it (it can be handy for Trish Scarborough, who does have access). The advantage of these cards is that they work on non-humanoids, but they are crutches nonetheless, enabling only part of the ideal handcuff build.