Chaff is an colloquial term for inexpensive and disposable units. They usually lack the ability to do much killing themselves, but they might be used to delay the fight, overwhelm the opponent, or bait mages into wasting casts of evocation spells to deal with them. On the other hand, they can also cause HP routs if they die in sufficient mass. Because they are usually numerous and easy to mass, they can also be good candidates to buff.

Also often mentioned is "siege chaff", units with otherwise low value but remarkably high siege strength that can help breaking down enemy forts. In the same vein, "patrol chaff" means units with good patrol abilities that can bring down province unrest or patrol out stealthy commanders/armies.