User blog comment:Khaladar/The Bonecrusher/@comment-3323227-20120608095220/@comment-5045990-20120608104434

Sounds great to me. But I'm guessing you'd have to remove the base ArPen then. If you would, you would still deal true damage to anyone with 100 armor or lower if you had Last Whisper, this item and pretty standard AD caster runes...

50% ArPen with masteries and LW: 50 armor left

ArPen runes (25) + masteries (6) + Bonecrusher (about 20, considering you have this one and Last Whisper) : True damage! And as a Panth player, my E would deal about 700-800 damage =3