How do you improvise monsters and NPCs?

[Ozreth]

Who has some good advice for coming up with baddies quickly? And I mean really quickly.

As a DM over the years I typically have a handful of things ready to throw at players, but every now and then you need to come up with something completely off the top of your head with no time to stat the damned thing out, which can be a pain in 3.x, especially at higher levels.

When this happens to me I typically just make a bunch of numbers up that I think are close enough and go with it (Unless it is a generic race/class, then I use the NPC lists from the DMG). While it usually works alright and my players either don't notice or don't mind, I would like to come up with a more definite method.

[Ozreth]

No one knows, eh? : p

[Infernalbargain]

This is a good foundation: http://www.d20pfsrd.com/bestiary/rules-for-monsters/monster-creation

If you compare to some of the printed monsters, the table's slightly weaker. The numbers for a 3.5 game shouldn't be much different. Then just fluff based off what the ideas that you want. Though if it can cast spells, try to make sure that most of the stuff it can cast is from the same list.

[Divide by Zero]

I'm a big fan of the "make it up as you go along" method, myself.

[pwykersotz]

One of two ways -

1) I'm always on my Laptop or PC, so I pull up my D&D tools site and set the filters to give me a monster that vaguely fits the environment. The one I used just last night was a Tendriculous (CR 6) that was causing problems at a nearby farm.

2) I crack a random Monster Manual and randomly point. Then I go forward until I hit an appropriate CR. Then I think of a fun justification why the random creature is in the area. Troll? Why would he be in a desert? Well obviously it's a Sand Troll that looks like he's sculpted from the sand. He's vulnerable to fire because it turns him to glass and acid because it breaks down the sand. Also, just for flavor, he has the power to merge with the desert sand, though it's a full round action to do so and a full round action to get back out. He "burrows" at 20ft.

Remember, even if the stats are near identical, a lot of players can't tell the difference between creatures as long as you describe them differently. And as long as you keep your party in mind and don't overdo it, you can bump a stat here and nerf one there. Not too many at once, the point is to hold it in your head, just enough to vary it a bit.

[Falin]

Say it with me, "just make up whatever's most dramatic" It works wonders when you're in a pinch.

[Thurbane]

DM Tools has a decent repository of user made NPCs, most of which are suitable to be as opponents on the fly (link in my sig).

[McSmack]

I don't even bother to use fancy DM tools or filters or whatnot. Just look up something with the appropriate CR and roll with it. Adjust the appearance/damage type etc to something fitting for the environment. Best thing about it is that because the appearance doesn't match anything they're used to the PC's don't know what to expect.

I've gotten so much millage out of the Winter Wolf, for instance. Need some creepy undead thing. BAM winter wolf, but change all frost damage to acid. Appearance looks like a large hunting cat of some type, obviously undead. The eyes are hollow and filled with a sickly green light. It's thick leather hide bears a network of rune shaped holes, through these holes you can see the same green light swirling around.

See, you're PC's would have no clue what the heck that is, and best of all the stats are already there for you to use. Just remember some basic undead qualities (neg/pos energy effects, immunity to crit/SA, etc) and you're golden.

Or change the element to fire and have them be big lizards with spines and crystal scales. Change the bite attack to a spiny tail slap, same hit/damage/effect, just cosmetically different.

[Godskook]

If you keep semi-detailed note-card-sheets for your NPCs, you can just 're-use' old ones as the need arises.

[Darth Stabber]

Usually if it's just mooks (and I didn't prepare heavily, or the party is "off rails"), i roll a d20 for most actions and see how I feel about them. I also have never thrown away a character sheet in my decade of playing (though i have lost a couple), and I have made ~150 characters of various levels, that I am unlikely to ever get the chance to play , so I have a lot to fall back on if I need something more than mooks.

Sometimes opening up a Monster Manual to the first monster you see of an appropriate CR works, but only if all of 3 conditions are met. A) you understand the weaknesses of the CR system, B) you use it sparingly, and C) you frame it well in story.

[Darth Stabber]

I don't even bother to use fancy DM tools or filters or whatnot. Just look up something with the appropriate CR and roll with it. Adjust the appearance/damage type etc to something fitting for the environment. Best thing about it is that because the appearance doesn't match anything they're used to the PC's don't know what to expect.

I've gotten so much millage out of the Winter Wolf, for instance. Need some creepy undead thing. BAM winter wolf, but change all frost damage to acid. Appearance looks like a large hunting cat of some type, obviously undead. The eyes are hollow and filled with a sickly green light. It's thick leather hide bears a network of rune shaped holes, through these holes you can see the same green light swirling around.

See, you're PC's would have no clue what the heck that is, and best of all the stats are already there for you to use. Just remember some basic undead qualities (neg/pos energy effects, immunity to crit/SA, etc) and you're golden.

Or change the element to fire and have them be big lizards with spines and crystal scales. Change the bite attack to a spiny tail slap, same hit/damage/effect, just cosmetically different.

My players have no idea how many wyrmling dragons they have faced at low levels.

[supermonkeyjoe]

I definitely re-use old NPCs, that guy who was the big bad at level 3 is now a mook at level 10, also re-fluffing monsters is always possible, the playes shouldn't don't know if a hit for 15 damage is 1d4+5d6 or 1d8+10 and it doesn't really matter.

[Darth Stabber]

I definitely re-use old NPCs, that guy who was the big bad at level 3 is now a mook at level 10, also re-fluffing monsters is always possible, the playes shouldn't don't know if a hit for 15 damage is 1d4+5d6 or 1d8+10 and it doesn't really matter.

To build upon that: the less the players see of your dice, the better.

A)the unknown builds suspense
B)it enhances reusability of certain threats
C)keeping the PCs wrong footed is part of your job description as GM.
D)Fudging die rolls can reduce immersion, and cause a number of other negative reactions and/or consequences. Unless they don't know the dice were fudged and you can keep your pokerface up.

And now I have that lady gaga song stuck in my head.