Take these from the army screen. Each limit is spent by its own section: leadership buys guardsmen, specialists and siege; dominance buys monsters; authority buys mercenaries.
Percentages exactly as the game reports them: type 420 for +420%. Leave a field blank when you have no bonus of that kind.
The stacks are lost in this order, weakest first, so the strongest units survive the most rounds and land the most hits.