Tissues damaged in battle can regenerate. Special chemical agents are injected to rejuvenate damaged cells. Each level of regeneration increases health 1% per round. For highly advanced warriors of the Swarm such as Guardian, Devourer, Lexx, Pancor , Usurper , Leviathan, Gigalord , Gigashadow it is even more difficult to achieve rapid regeneration. therefore, they get 1% of recovery per round with the development of the two levels of evolution.