Flash Heals and heroic Halfus
I was assigned as holy to tank heal on this encounter and the only way I could mange it was by absurd, copious use of flash and greater heals while in Serenity interspersed with PoMs, CoHs, etc. In order to support this I put lightweave on my back, Power Torrent on my weapon, and use the Mandala of Stirring Patterns/Core of Ripeness trinkets.
The strategy was to button mash the above spells using the Core as often as possible, and between 50-70% mana wait for two or three of these to proc. The epic megaton of int would nicely juice my shadowfiend (not to mention help in healing the tank) and I'd get enough mana back to last through the first major push of the encounter.
I do prefer not to flash heal, but when you've got to balls-to-the-wall go for maximum throughput on a single target what is better than FH FH GH POM repeat?
My only regret is I'll never rank on this, as single target healing (for the most part) a tank with Malevolent Strikes will never get you fat, juicy numbers.