Pestilent UO uses a standard AOS era Champion Spawn system with some very minor changes.
Spawns can be found in Britannia and the Lost Lands. To activate a spawn a player with Knight of Valor must use the Valor virtue actively on the skull in the middle of the altar. Once the spawn is activated, a red skull will appear along the edge of the altar and various mob types will begin spawning. The skulls that appear around the altar help track the progression of the spawn. As you kill the spawn, white candles will appear in the altar's center. Each white candle represents 20% advancement to the next red candle. Upon reaching 100% a red candle will appear on the edge of the altar. If you do not kill enough spawn within 10 minutes of the first monster being killed the white candles will reset to 0%. If you do not advance at least 20% at a single level, one red candle will disappear and the spawn will begin moving backwards. Once you have gained enough red candles, the spawn will increase to the next level. Each spawn consists of 4 levels which grow in intensity and spawn tougher creatures, which in turn will require fewer kills to advance the spawn. When the altar is full at 16 red candles, the Champion Boss is summoned. Once the Boss is defeated roughly 80,000 gold will spawn on the ground in a radius around the slayed Champion, and a total of 6 power scrolls will be awarded to players whom registered damage to the Champion. If the players whom received a power scroll were protected by a Knight of Justice, the protector will receive a copy of that power scroll. This allows for 12 total power scrolls to be collected from a spawn.
The following items have a chance to drop as a prize when a player slays a Champion Boss. These items will not drop in Illshenar champion spawns.