Transitioning from phase 1 to 2, I ensure everyone is topped before the gigaflare itself but I won't bomb heals for the gigaflare damage that follows, instead I'll be making sure both tanks are topped with regen. From then on, if the transition was after a megaflare my medica II will still be ticking and thus will top people up in good time along with fairy heals. If it was after earth shakers then I'll typically cast a medica II from the middle of the arena as the first set of orbs appear, the OT will generally have more than enough enmity on the add that hate won't be an issue unless something is going drastically wrong elsewhere. That also gives me good time to help the SCH on the MT for the flare breath that follows.

For Megaflare>Tower>rage in phase 2 I run a somewhat inefficient but safe method of healing this. I'll hit Divine seal a few moments before Megaflare starts to cast, then Medica II as Megaflare is casting, from there I'll position myself either with the circle stack or to the side and regen the MT+squishiest 2 stack, then start a regular medica cast roughly as the unavoidable (Plumes > Unavoidables > Circles) megaflare hits land. This ensures my medica hits between the circles and the tower making sure that squishier sorts don't die from the combination of both hits. From there I can do two things from the following, cure 1 the MT for the flare breath (Or someone else if they are at risk of dieing to rage), cast another Medica or hit a Cure 3 on the stack. A messy megaflare or a few people with 2 stacks usually means more AE healing. As mentioned above, the critical thing to keep in mind is that you want to ensure your big healing is done before Rage completes the cast or you will end up with massive hate on the shadow. Typically a cure on the MT followed by a medica does the job nicely.

From there, I'll immediately move either to the middle, or away from the Shadow that's about to pop to ensure it doesn't get a cheeky hit on me whilst the OT is tagging it.

TLDR - http://www.hitbox.tv/video/515743/description

GL <3