EQUIP a fusion charge. FIRE the charge to set a slow-acting burst through the wall. The burst does heavy damage to anyone caught in its area.
[X] Rolling Thunder is an incredibly powerful initiation tool for your team. Good communication and timing paired with movement/vision impairment make for an easy team wipe.
Breach's [Q] Flashpoint must be cast against a wall, but can be done so from range.
Watch your minimap during cast as it will indicate the location of the AoE flash on the opposite side of the wall.
Due to the long activation time, [C] Aftershock is incredibly hard to hit on it's own. Try to combine it with teammate movement/vision impairing abilities.