Basically, the priest does nothing until I click a heal key.
The mage does Arcane Blast x4 then Arcane Missiles, simple sequence.
The shaman does Flame Shock, Lava Burst, Chain Lightning and Lightning Bolts, priority except for the shock which is when the dot expires.
The warlock goes Haunt, Agony, Corruption, Unstable Affliction, Immolate and then Sh.Bolt spam, priority but only refreshing dots as they expire.

So the Shaman doesn't Chain Lightning until the 3rd click.
In the above example, the Druid doesn't Swipe until the 5th click.
The Priest can take heal aggro, but the Mage and Warlock are casting single target spells at the Druid's target.
It might be a nice macro overall, but the Chain Lightning on the 3rd click requires some AoE threat very early from the druid.