Orc by Saad Irfan.
Orcs have a limited useful life in in a campaign. Once the heroes get to a high enough level, your basic orc is no longer a threat. The skullsplitter makes orcs relevant again, at least for a few more levels.
Skullsplitters
Skullsplitters are cruel and cunning creatures. They defy standard orc dogma, choosing to wield slightly smaller weapons, so they can effectively employ shields. They make up this offensive deficiency through training and pure fury. It is common to find skullsplitters taking on multiple opponents and winning.
Thier signature maneuver is to headbutt their enemies, often crushing helmets and the poor creatures within. Most skullsplitter's faces show scars of this nasty habit.
Skullsplitters realize the value of trickery, and often ambush their opponents with a cadre of choice stealthy orcs (Standard orc stats, +3 to stealth, no change in CR). If the skullsplitter has only brutes at its disposal, it will hide and wait until the enemy is engaged before entering combat. They prefer soft, easy targets, and will attempt to crush or disable those pesky wizards first.
Notes
Several skullsplitters operating together can keep your party in stunlock and will result in a player flipping over a table. You should combine them with a mix of other creatures.
Design feedback by Steve (@thedicenerd). Who started this whole process by asking "Why do you have a campaign about orcs ending with a hobgoblin warlord?"
Offensive CR is 8 while Defensive CR is 4
Download the PDF here.