Enemy Shield Recharging and not Taking Damage
So I've really only noticed this on the higher level enemies like elites, gunships or terran fighters (basically anything with high HP). If you deplete an enemy shield and then let it start recharging then it seems to ignore incoming damage during the recharging phase. To date I've not been able to stop an enemy from fully recharging its shield despite hitting them with a fully upgraded beam laser 2 and missiles. Once recharged there also seems to be a few seconds before it starts registering damage again.