Attacking is done automatically once you select attack or click the \'attack\' button on the left-hand panel, until you deselect the unit.
On an interesting note, when I right-click a unit it deselects it, so my attack button doesn\'t work. I remapped attacking to the keyboard \'a\', but you could just left-click the rat and use \'attack\' button on the left-hand panel.
If you are too far away messages about being too far away will pop up. After a linkdead(server boots tons of players) monsters are invulnerable for a while. They don\'t do anything - this is so people can come back on and load the world without dieing.
