I ran the kobold lair with only 4 players (elf ranger, human paladin, human wiz, tiefling cleric), and considering how badly they were doing with the kobold road encounters I figured it was a definite wipe. However, prior to the session I spent a bit of time emphasizing that teamwork and tactical movement were so important to 4e, I guess it sunk in. They used the ranger's stealth to scout the outside of the lair (risky) and were able to kill the slinger and dragonshield before they could act by using a surprise round and winning initiative. They demolished the outside kobolds in 3 rounds, and stealthed in for another surprise round.
Even still, Irontooth nearly killed them all. The paladin was tanking like a pro, and the ranger was using his elven racial to shift through the difficult terrain of the waterfall using nimble strike to basically make himself untargettable (I ruled the waterfall blocked line of effect). The wyrmpriest took heavy damage early and retreated to a corner, and only had a clear shot at the cleric who "tanked" the fireballs with the tiefling racial resistance. All in all, it was very close. They missed with all their dailies, sadly, and had to chip away with at wills and burn a couple healpots I let them buy before leaving town on the paladin.
Even still, Irontooth nearly killed them all. The paladin was tanking like a pro, and the ranger was using his elven racial to shift through the difficult terrain of the waterfall using nimble strike to basically make himself untargettable (I ruled the waterfall blocked line of effect). The wyrmpriest took heavy damage early and retreated to a corner, and only had a clear shot at the cleric who "tanked" the fireballs with the tiefling racial resistance. All in all, it was very close. They missed with all their dailies, sadly, and had to chip away with at wills and burn a couple healpots I let them buy before leaving town on the paladin.