well on kethis 16 man if you are using 2 gardians and shadow you need at least 1 gardian in aoe tank spec , then 2nd gardian can go hybrid or full defence .... just chucking that out there but that is a singel , fight !!!
Err, as I far as I can decode that cypher "you need at least 1 Guardian in AoE tank spec". Whatever do you mean, care to provide such a spec?