Most people here should be familiar with the Guardians of Icecrown. These are adds (two in 10 man, four in 25 man) that Kel'thuzud (the final boss of Naxxramas) spawns at about 40%. They have a nasty habit of ripping even well geared OT's apart if the healers slack off as you get down towards 10%, due to a stacking debuff, so here is an easy way to avoid this.
Get aggro fast, and drag them onto KT's throne. Try and get them to walk through the middle of it. They will despawn and your OT's can go back to doing mediocre DPS without the hazard of Guardians wiping the group at the last moment.
Enjoy.