I would like to see player can recruit bid mercenaries contract prompt by random event and the advantage is appear to the location where you wanted to deploy to. This restricted to high level creature only and when contract expired system will prompt you to renew contract or not.
eg. 2 vampires have 5 turn duration contract which cost 100 gold
if above 2 vampires die in combat the mercenaries contract ceased. if above 2 vampires left 1 vampire survive in combat contract continue and player still will pay 100 gold even is under-strength.