What mods do you use?

[Swiss Mercenary]

Never hurts to have Omen up anyway. Lets you get a good look at where your threat is in relation to the tank's. I use Omen primarily to monitor DPS threat levels so I know who to hit with a Salvation, but our tanks produce amazing TPS, so it's rarely an issue.

Blizzard threat meter mouse-over-the-boss when I feel I'm close has always been enough for that - at least, for me. I usually don't even DPS.