The Bountiful Swarm

Once per battle, at the start of your hero phase, pick 1 enemy model within 3" of the bearer and then roll a dice. If the roll is greater than that model's Wounds characteristic, it is slain. If that model is slain and had a Wounds characteristic of 4 or more, before it is removed from play, you can add 1 BEASTS OF NURGLE unit that has 1 model to your army and set it up within 1" of the slain model. The BEASTS OF NURGLE unit can only be set up within 3" of an enemy unit if the model was within 3" of that enemy unit when it was slain.