"The blood shall be a sign for you on the houses where you live; and when I see the blood I will pass over you, and no plague will befall you to destroy you when I strike the land..."
An action is anything which uses action points - skills, spells, etc. Actions have three main components - effect, action points needed, and range. To carry out an action you will need enough action points in reserve to carry it out. Actions are represented on the user interface by a row of icons along the bottom of the screen.