Each time a DAMNED unit from your army with the Dark Pacts ability is selected to make a Normal or Advance move or declare a charge (excluding units that arrived from Reserves this turn), it can make a Desperate Pact (see below). If it does, until the end of the phase, add 2" to the Move characteristic of models in that unit and add 2 to Charge rolls made for that unit.
Desperate Pacts
Each time a unit makes a Desperate Pact, it must first take a Leadership test; if that test is failed, that unit suffers D3 mortal wounds before any effects of that Desperate Pact are resolved.