They have a special name, special graphics and get. Monster Infrequents (MI) are the rare variants of such items. These items can be of broken (grey), normal (white), magic (yellow) or rare (green) quality. Probably the most sought Monster Infrequent item are the Stonebinder Cuffs which drop from Gorgons since they give +1/+2/+3 to All Skills depending on the Difficulty. Items > Monster Infrequents Certain types of monsters get to use their own special armor or weapons instead of using standard items (like Centaurs use the Centaur's Cuirass as body armor). Being rare items, they can be improved with a monster charm or relic shard. They have a special name, special graphics and get various fixed affixes/suffixes in addition to several random ones.
Certain types of monsters get to use their own special armor or weapons instead of using standard items (like Centaurs use the Centaur's Cuirass as body armor).