[Jack Simth]

Well, a normal party can arrange to pass reasonably safely through Tucker's Kobold territory... but hurting a significant number of Tucker's Kobolds is difficult.

They're in tunnels too small for your entire party (how many parties are made entirly of Small creatures?).

They're in tunnels that fold back on themselves in ways only Tucker's Kobolds know about... and oh yeah, there's carefully concealed murder holes between them, so at any moment, a kobold can drop, say, a flask of lit oil on top of you. Or just the oil. Or flood a tunnel floor with oil, and drop a tindertwig on top of it.

You find a way to attack them, they retreat. Every time. It's the first thing they do when they find out you have a way to strike back. It's their strategy. One thing doesn't work, they try another. They have dozens. Arrow slits with flaps on their side. You approach, they close the flaps (alternately, they fire at you in three kobold teams: the first readies an action to close the hatch after the archer fires through; the second readies an action to fire through the hatch after it opens; the third opens the hatch - open, fire, close - all on the same initiative - oh yeah, and the hatch is sized so the kobolds, with their small selves and their slight build, can just barely get a mediocre shot off - so they deny line of effect for spellcasting even while "open" and still grant the kobolds cover. Oh, and they communicate, and have a watcher - you're on one side of the room, it's the covers on the other side that are open; the ones on that side have largish rocks laid against them, and are latched/barred from the other side). Rooms that cave in when a kobold watching from another room pulls on a particular rope (cave in rules are nasty). Rooms that seal up, air-tight, so you suffocate over the course of a few hours. Slides coated in grease, that end in pits, with pet gelatenous cubes at the bottom. They harry you constantly - you can't rest or stop to prepare spell slots left blank (unless you pull one of the tricks, or a variation on it, listed earlier).

Now, resist energy will take care of the various fire-based tricks... except using up the air in the room. Protection from Arrows will take care of the shots for a time. Very, very little will deal with a cave in. Almost nothing deals with the small sized tunnels. Oh yeah, this is done by 10 CR 1/3 kobolds, 5 CR 1/2 kobolds, and 1 CR 1 kobold. They had several months to prepare. Officially, that's an encounter level of 6. And it's done in such a way that officially, a 1st level party of four gets 513 xp each. As does a 6th level party of four. And they have a pretty good chance of taking down an 8th or 10th level party (a 10th level party of four would officially get 0 xp; an 8th level party of four would officially get 50 xp each).

Sure, it's realistic guerrila tactics... but it's also mean, unbalancing, DM tricks.