If models have more than 1 wound then casualties are removed as follows. Imagine that a unit of Minotaurs suffers 5 wounds from arrow fire. Minotaurs are big monsters and each model has 3 wounds. The arrows would fall randomly among the unit, possibly wounding several creatures, but for our purposes we shall remove whole models where possible. So, 5 wounds equals 1 model dead (3 wounds) with 2 wounds left over. The wounds left over are not enough to remove another model, so the player must make a note that 2 wounds have been suffered by the unit. If the unit takes another wound from some other attack, then another Minotaur model is removed. It is obviously important to keep a record of wounds taken by units such as this.