A misconception about Hyenas is that they are primarily scavengers. They are not -- they are hunters, and pretty aggressive at that. I read more than once that the traditional relationship between lions and hyenas as popular culture has it is actually backwards: hyenas mostly hunt, and lions mostly steal their kills.

Also, a single lion (or two) facing a pack of hyenas is in dire peril. Hyenas are clever, strong and dangerous. There are YouTube videos about this.