Your biggest weakness will be Fear.
Cleave type opponents will hurt, but you'll hurt them too.
Battlegrounds are a lot more random then Arena which will help you.
As you gear up, you'll become even nastier.
I like the idea of 4x Felguards each with Cleave against pesky melee.
Soul Link will help keep you alive.
I'd personally go Affliction with a team, although I was a 1-box Felguard lock through most of the BC raid content and that was quite fun too.
There's a video from a few years back, a Disc Priest (dwarf) and 4x Warlocks (gnomes).
It's very good quality and pretty fun to watch.
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