Up to now the only cast bar I've been concerned about is the cast bar of the mob/player I'm targetting.

At the risk of appearing stupid I'd like to understand why seeing the cast bars of your slaves is so important. What information is it providing you? or rather In what way does that information benefit your potential.

At the moment I'm using visual cues. For example - i've hit flameshock, but only two have made it on to the target - at that point I'll have a quick look round my slaves to see why (it could be a miss or a toon out of range). A volley of lightning bolts goes off - but there doesn't seem to be enough of them, again it's a quick look round the slaves.

I used to be of the opinion that I woud run with as few mods as possible.... but I recently tried out healbot on a solo healing toon - and it improved my reactive healing just by having the icons right next to my char (rather than clicking over to the stock gui party and clicking that). So I'd really like to understand the importance of slave casting bars.