The Dreadhorde deals 0.5% of its Effective Combat Strength in damage to the Security of the Region it is located in.
If the Security is reduced to zero in this way, the remainder of the damage is dealt to the Economy of the Region.
If the Dreadhorde is not attacked during the same Action Phase (1st or 2nd) or a subsequent action phase, it regains +20 Health at the start of the Recovery phase.