I think what he is getting at is this -
In City of Heroes / City of Villains, you are not able to stack most buffs from the same caster...
The way around this limitation involves buffing your team before you enter a mission, and then again once you are inside the mission...the game seems to treat you as a different caster, allowing your buffs to stack on your team...
This works best for buffs with long durations and short recharge times, such as Force Fields, Sonic Shields, Cold and Thermal Shields, etc...
Hope thats clear enough
Let me know if you guys need to know anything else...