The only engine we have ever had has been jury rigged from the get-go... I will see about trying to get a better one up, but for the meantime check out the conditions.lua
.lowest, .tank are going to be your main things. You can raid check with lowest.health(6,80) with i1 being playerCount and i2 being playerHealth
e.g.
Code:
{ "Circle of Healing", "lowest.health(8,60)" },
This is entirely off the top of my head, so the real working may be different. I know for a fact that the Restoration Shaman has the examples inside it, however. I built that one a while back as a proof of concept.