When troops are defeated in a battle outside of the player's turf (e.g. attacking other players or during Skirmishes), 60% of the troops (highest tier troops) will be sent to the Infirmary as long it is not at full capacity, the remaining 40% will be dead, unless there is space in the sanctuary to take them, in which case 38% of troops (highest tier troops) will be sent to the sanctuary.
When troops are attacked when defending a tile or inside the player's turf, all injured troops will be sent to the Infirmary, providing there are still Infirmary spaces available.
If troops are defeated when the Infirmary is at full capacity, the troops will be dead, unless there is space in the sanctuary, in which case (80% if defending, 38% if attacking) will be sent to the sanctuary to be revived.
A majority of wounded and dead troops are revived in Darknest rallies.
Upgrading the infirmary will increase the capacity of the infirmary. At Level 25, the turf will receive a bonus Army Max HP increase of 5%.
Infirmary Healing Speed can be increased with the Field Triage I and Field Triage II researches, for a total increase of 95%. The Strix Familiar's Blood Bag skill can increase Healing Speed by another 25%.