Glyph Renew.
Contrary to popular belief, renew is a powerful if used right for disc. Crits proc aegis and you can use borrowed time to get an extra tick on the renews you throw out (remember, borrowed time is only consumed when a cast time spell is used, all instant casts will receive the bonus haste) glyphed, you'll hit the next renew tick (with borrowed time and the 5% haste buff) at 1.66% haste and I have that reforging out of all the haste on my gear.
I'm not saying blanket the raid in renews, but glyphed renew applies ~60k over 8 seconds for me. its good for staggered raid damage especially only costing 7.8k mana.