2011-09-22 : If Unbreathing Horde enters the battlefield from a graveyard, it will count itself when determining how many +1/+1 counters it enters the battlefield with.

2011-09-22 : If Unbreathing Horde has no +1/+1 counters on it (but its toughness is raised above 0 by another effect), any damage dealt to it will still be prevented, even though no counter will be removed.

2011-09-22 : Only one +1/+1 counter will be removed, no matter how much damage is prevented.