Deathwatch Veteran w/ heavy thunder hammer

The bearer has a 4+ invulnerable save.

Each time an attack made with a [DEVASTATING WOUNDS] weapon results in a critical wound, the attack sequence for that attack ends and the target unit suffers a number of mortal wounds equal to the D characteristic of that weapon. These are inflicted after resolving any normal damage inflicted by those attacks.  Mortal wounds inflicted by [DEVASTATING WOUNDS] weapons can damage a maximum of one model for each critical wound; any remaining mortal wounds inflicted by that attack are lost.  Example: An attack made with a [DEVASTATING WOUNDS] weapon with a D characteristic of 3 results in a critical wound against an Intercessor Squad, so inflicts 3 mortal wounds. The first 2 mortal wounds are sufficient to destroy 1 Intercessor model, so the remaining mortal wound* is lost.