Haywire Bolts

When you give a model this Relic, select one bolt weapon (see Codex: Space Marines) that model is equipped with. When the bearer shoots with that weapon, you can choose for it to fire a haywire bolt. If you do, you can only make one attack with that weapon, but when resolving that attack, if it is made against a VEHICLEunit, an unmodified wound roll of 4-5 inflicts D3 mortal wounds on the target in addition to any other damage, and an unmodified wound roll of 6 inflicts 3 mortal wounds on the target in addition to any other damage