Only killing enemies in adventure/ mission is quite boring, can add a building like Prison to imprison defeated minion or mini-boss? Perhaps.
A prison is upgrade to level 10, each level expand 2 slots of prison cell.
Inmate have their time remaining before being released.
They can be used either as labor force to boost overall economy for 0.5-1.5% per 1 inmate
or used as one-time use Mercenary for next adventure/mission.
