How to make a bad guy really challenging?

In my DW game, several times I've had a big monster, described him as very scary, then seen him get destroyed really fast by the players. For example, I created a giant tunneling serpent, smashing apart a house the players were in while they tried to get away. I described him as a primal force of fury. They were scared, until the fighter jumped in, the ranger shot an arrow, and the wizard shot a fireball. He was dead.

The players stopped for a second and said, "huh, I didn't think that would be so easy".

I can describe scary monsters, but they just don't live long enough to do much of anything. It seems like if the players get to act first, and they don't fail their rolls, the scary monster is dead before it acts.

What am I doing wrong here? Any suggestions?

Another example might be: let's say I want to create a vampire lord or something. He's supposed to be totally badass, as in, not really possible to defeat without a trick or extensive planning or something, but he IS defeatable in theory. In the rules-as-written, he'd only have like 18HP/4 armor at most, which is less awesome than a L5 fighter, right? Even with scary moves, wouldn't he just drop really fast? (because my players might not fail enough rolls for him to exert his badassery.)

The wall of the house are crumbling, make the fighter do a defy danger to avoid the debris before he does a Hack n Slash. His sword hit the snake big scaly flesh, tell him how little it affect him, but that he succeed at turning the snake attention on him.

The more you give details like these, the more your players will need to roll, giving you more moves and they will also try to find a weak spot to be able to do any damage.

My favored aproach with ''Bosses'' is 3 fold.

* Characters usually need to defy danger to be able to get a hack n Slash.
* Many hits won't do anything against it, they need to find a weak spot.
* The monster moves will have the character defy danger constantly.

Have them do some special moves that will ''stop'' some characters temporary. Fighter is stunned and the wizard his busy casting his spell. The serpent open his mouth to swallow him whole, what do you do Ranger ?

Another example might be: let's say I want to create a vampire lord or something. He's supposed to be totally badass, as in, not really possible to defeat without a trick or extensive planning or something, but he IS defeatable in theory. In the rules-as-written, he'd only have like 18HP/4 armor at most, which is less awesome than a L5 fighter, right? Even with scary moves, wouldn't he just drop really fast? (because my players might not fail enough rolls for him to exert his badassery.)

Fighter you cut the vampire head, but he turns into a strange mist. You are slowly choking. What do you do ?

Or

Your arrow strike straigth into the vampire head. He look at you with an evil smile, as if nothing happened. You feel your weapon starting to burn into your hands, what do you do Ranger ?

The first thing to remember is, HP are used only when characters CAN do damage. Have them work to know how to do damage.

J. Trudel has some awesome adivce!

One of the things to remember when running a "badass" creature is to force the players to roll often; every time they roll you have a chance for another GM Move.
As an example the players in our group fought a demon-creature beneath an abandoned church the other night:

Opening Move (GM): The demon's unbridled fury unleashes a blast of hellfire throughout the room; everyone Defy Danger.
The fighter rushes forward and I remind him of the corona of hellfire that remains around the demon; Defy Danger in order to Hack & Slash.
By the time the fighter makes his first attack he has had to Defy Danger twice. In our scenario the fighter took 8 points of damage that ignored armor from the initial blast, but stayed on his feet (rolled an 8), then took another 7 points from the corona (rolled a 9) and was forced to choose between: take 5 more points but you may Hack & Slash, or get knocked prone at the demon's feet. Feeling like his bad luck was behind him the fighter made his attack (rolled a 8). He inflicted 12 points of damage but the demon's armor rating of 4 knocked it down to 8 (the demon required a sanctified weapon to bypass his armor; the heroes suspected this but the fighter was unconcerned). The demon struck back, d10+3 ignoring 3 points of armor; of course the fighter rolled a 10 and down he went.

These were the very first actions of the combat; no one else had even acted yet! I looked at the other players and said "Before Bael makes his Last Breath roll, what are you guys doing?" Of course the heroes had no idea that Bael actually did managed to take more than half of the demon's hit points, but by that time, they were already considering options of how to escape with their lives from this "badass" demon!

Yes, all good advice. Remember that you are making Moves for your monster, not just dealing damage when a player rolls poorly. If the monster is fast, make him fast. Describe him rushing past before they can react. Deal hard moves (damage, for example) if the fiction calls for it. You can say things like "he easily turns aside your strike with supernatural grace. You'll need to create an opening to even hope to hit this guy..."

Monsters aren't just numbers. In fact, they have very few numbers. You gotta make them match your vision through description and consequences. The consequences of a roll aren't always the same: if a monster is dangerous enough, ask yourself "what's the worst that can happen? What's the best that can happen? The best result of attacking the Swordmaster Vampire Lord is not the same as the best result of fighting an ordinary kobold. Maybe the player is not triggering Hack&Slash, maybe she's Defying Danger just by getting near this creature. Say "you plunge your sword into it and it barely flinches. It grabs your arm and pulls you close, pushing the sword deep into itself and laughing. Roll your damage and take four damage yourself, as its claws rake your face."

Does this make sense? You gotta recalibrate your idea of best/worst case rolls. If a creature is badass enough, sometimes the best that a player can hope for is to suffer less harm than they dish out. If you're having trouble, think of these as custom moves: "When you Hack&Slash the Swordmaster Vampire Lord, you suffer 1d4 damage even on a 10+. He's just that good."

When you battle the Living Whirlwind, debris fills the air. Suffer 1 damage every time you act.

When you Hack&Slash the Dark Lord's Avatar, the best you can do is a 7-9 result. He is evil incarnate, and has been fighting heroes for a millennium.

These are all pretty heavy-handed, but hopefully you get the idea. Sometimes it's as simple as calling for a Defy Danger just to attack. Sometimes it's more hardcore than that. You're not penalizing the PCs just for the sake of making your "boss battle" difficult. Your job is to fill their lives with adventure, but also to portray the world honestly, right? What does an honest portrayal of this enemy look like? I think it's 100% legit to say, mid-combat, "Hold on guys. This is The Greatest Swordsman In The Land, right? Does it feel like that to you guys? Me neither, I feel like we're making him a pushover and he's supposed to be powerful. I messed up, he's more badass than this, let's do this right. Sorry about that."

Be honest! To your players and to the fiction you're all creating.

Mostly: what others have said.

Also: I find that it's really help to write out the special qualities and moves of my monsters in a way that makes them fictionally dangerous and that changes the nature of the fight.  Like, don't just rely on the monster's hit points or armor to make it tough. Give it moves like "ignore all but the most well-placed blows" or qualities like "can only be killed by a blessed crossbow bolt" (hello, rakshasa).   Don't just give you vampire a move like "drain blood from it's victims;" go big with something like "Drain the blood, life, or free-will from its victims."

With that in mind, here's my take on your badass ancient vampire lord: http://codex.dungeon-world.com/monster/629012

If the party doesn't make an execute and flawless plan, they're not going to get the drop on this thing. If the don't have the drop on it, it can easily escape just about anything (by clouding minds, turning into mist, or moving with impossible speed), turn the PCs against it each other (by clouding minds or draining free will), or simply beat them into a pulp.

It's not always necessary to write out moves and qualities so aggressively; once you're more comfortable with how fictional details can influence a DW encounter, you'll probably just be able to "wing it" with a good sense of what a creature should or should not be able to do. Personally, though, I find "statting up" a badass monster with game-changing qualities and moves gives me a sense of freedom to play them with integreity, hard and mean. I don't know that I'd feel that same freedom if I was just making up what the monster could do on the fly.

This is a fantastic discussion. I've only run 2 sessions of DW, but I'm completely hooked!

One Question: if you were to make custom moves for a Tough/Fast boss-monster, would you present those rules to the players in writing? Like, print them clearly on a note-card and put them next to the Basic Moves sheet for all to see? (i'm still getting the hang of 100% player-facing rules)

Let me sum up what I've learned so far:

1. Call for lots of defy danger rolls if something is very dangerous. Can give the bad guy more "turns"
2. It is ok to have Hack and Slash not deal damage if it doesn't make sense fictionally. Or rather, he just rolled a defy danger strength and didn't realize that is what he was doing.
3. I don't have to let the characters go "first" even if no one is surprised. If someone is fast, he just acts quickly, immediately putting the characters on the defensive.
4. Write down moves and qualities of monsters that describe how they are hard to kill, if they are.

Thanks so much for all your help! I love the vampire lord Jeremy

I don't show players my custom moves. When they're triggered I will usually paraphrase the move or sometimes even read it out loud to them. You could totally present it on a notecard when it's triggered, though. Telling the players "I wrote a move for this" often gives more legitimacy to edge-case rulings tor some reason, like the fact that you wrote it beforehand is somehow more official or something, than just going "umm, roll plus Dex..."

1. Call for lots of defy danger rolls if something is very dangerous. Can give the bad guy more "turns"
2. It is ok to have Hack and Slash not deal damage if it doesn't make sense fictionally. Or rather, he just rolled a defy danger strength and didn't realize that is what he was doing.
3. I don't have to let the characters go "first" even if no one is surprised. If someone is fast, he just acts quickly, immediately putting the characters on the defensive.
4. Write down moves and qualities of monsters that describe how they are hard to kill, if they are.

All correct, except #2. Remember, it's not Hack&Slash if it doesn't meet all the trigger conditions. I'm not advocating robbing players of their moves, just saying that if you envision the monster as too fast to trade blows with, describe it leaping away before asking for a roll. Stuff like that. Once you've said "okay, roll H&S," you're kinda obligated to give the player what they earned. On the other hand, if you tell the player beforehand "this guy is so tough, he will hurt you even on a 10+, though a miss will hurt more," then it's fair game. In that case you're Telling The Consequences, yeah?

Basically, make sure you're not hitting them with a 'gotcha,' that's all.

You've seen the 16hp Dragon right?

Couple additional quick points:

1: Remember there are no "turns", have your bad guy act as often as you want (or as fictionally appropriate).
2: Dangerous environments can also force more dice rolls on the players.
3: The tougher the creature (or the encounter) the harder the GM Move.

I've even modified Basic Moves for really tough opponents. For example, Hack & Slash still causes damage to the PC on a 10+ (although I use a smaller amount of then the creature's normal damage).

Wimpy opponent:
Thief: "I step behind him and stab him in the back."
GM: "Great, he's distracted by the Fighter. Go ahead and deal your Backstab..."

Badass opponent:
Thief: "I step behind him and stab him in the back."
GM: "He whips around, snarling, his claws flashing like lightning. Go ahead and roll Hack&Slash..."

Incredible God-Like opponent:
Thief: "I step behind him and stab him in the back."
GM: "Not so fast! He moves like quicksilver and darts out of range. I suppose you could leap after him, but his claws are everywhere. You'll have to Defy Danger to get close enough to attack..."

All simple ways of demonstrating enemy skill. On top of all this, you can go with the custom-moves-modifying-Hack&Slash results, too. You've got a lot of options when portraying your beastliest!