Storm Speeder Hailstrike

Each time this model has shot, select one enemy unit (excluding MONSTERS or VEHICLES) that was hit by one or more of those attacks. Until the end of the phase, each time a friendly ADEPTUS ASTARTES unit makes a ranged attack that targets that enemy unit, improve the Armour Penetration characteristic of that attack by 1. The same enemy unit can only be affected by this ability once per phase.