Back in 4th ed, there were a few weapons/units that could ignore invuln saves to one degree or another. Warscythes from Necrons, Dread Axe from CSM 3.5 (Man I loved that weapon), psycannons from the old Demonhunters, and several others.
Since I basically ran away from 5th edition like it was a particularly randy Bloodthirster once it broke down to musical chairs, my current codex knowledge is pretty lacking. So, my question is: What units are out there now that can ignore Invuln saves? The Dread Axe was lost with the greatest codex mankind will ever see, and the new Necrons/Pokemon Trainers' warscythes don't ignore invulns anymore to my knowledge, so I can't think of any that actually can ignore invuln saves now, except for the Vindicadre assassin.