Orc cards may drop from any monster below level 90. While not specializing in tanking like Yeti or damage dealing like Skeleton, the Orc is an evenly-distributed Damage Dealer + Tanker in the tier 2 pets.
The main build is focused on high P.def. and P.atk. with significant uses of passive P.def. and P.atk. skills. Many times, some active skills are used but the specific skills can vary by level for maximum usage. Unity, as well as the card and armor passives are a must in the Orc skill set.
Another build option, mainly aimed towards pet classes, is the all pure Damage Dealing build. One uses only a 2h Axe and Str ring. This build adds more to damage than armor can, with a slight boost to HP for occasional hits. Without adding points for HP or P.def, one will have enough to add points into OB Str and possibly OB Dex. It requires one (or someone in the party) to already have a tank ready to take hits; it should not have ANY points in Threatening Essence.