Transference is one of the 8 damage types. Transference beams appear as stretched out Yin-Yang symbols of various colors. Transference weapons, unlike other damage types, are used to heal and not hurt. Shield Monkeys receive special bonuses when using transference weapons. The negative damage it does to the target is equal to the damage it does to yourself, effectively transferring the shields from you to your target.
Transference diffusers are used to dampen the effects of damage on the ship that is transferring the shields from itself. Firing on a fully healed ship or into space does not consume sheilds.