Blooood...

[Squirrelloid]

Note that:
-Sites with negative effects apply their negative effects whether you find them or not.
-If you have a province with random unrest each turn and its in your dominion, it probably has one or more blood sites of this type. (Unrest should be a multiple of 5 if you tax low enough or patrol enough to reduce unrest to 0 otherwise).
-Some sites which generate unrest do have good effects - like enter to summon a devil.

[WingedDog]

militarist
You choose the mage in the lab, press Shift+M and choose ritual.

[Viajero]

Excellent thread. This should be added to the Strategy lists sticky.