When attacking, each attacking Gorgon, in addition to the direct damage, has a 10% chance to instantly kill one unit in the enemy stack. (Exception: Necropolis troops, gargoyle, golem, and mummy, which are immune to this Gorgon ability). The number of units destroyed depends on the number of Gorgons and varies between 1 and N/10+1 (where N is the number of Gorgons. For example, 31 "bulls" can additionally destroy from one to four creatures in the attacking squad). Or it might not destroy any, like that. ;)
That is, if we have:
01-09 Gorgons - max. 1 can be destroyed;
10-19 Gorgons - max. 2 can be destroyed;
20-29 Gorgons - max. 3 can be destroyed...
Charity suffereth long, and is kind; charity envieth not; charity vaunteth not itself, is not puffed up,
Doth not behave itself unseemly, seeketh not her own, is not easily provoked, thinketh no evil;
Rejoiceth not in iniquity, but rejoiceth in the truth;
Beareth all things, believeth all things, hopeth all things, endureth all things. Charity never faileth...