The Black Tongue ?

I have recently been putting together the basis of a Warriors of Chaos army for my next tournament.  The one item that I am struggling over is The Black Tongue.  

On first glance it looks like a must have item, at 50 points my plan was to put it on my exalted BSB.  Combined with the Infernal Puppet this could be a lethal weapon.  


The reason for it being on the BSB is that both hero level Sorcerers are loaded with arcane items, and my lord is a Daemon Prince which cannot take any magic items.

Then we read the "small print", owning character takes a wound that may not be saved by any means.  So in order to hopefully remove an enemy wizard I put my character on half wounds giving away around 100 victory points.  If the roll of a 2 on the miscast table removed both the wizard and its mount, then I could understand anyone taking this item.  

For example a Dark Elf Sorceress Lord would be around 300 points meaning that I benefit 200 points.  But it all depends on my opponent rolling in my favour on the miscast table, then myself rolling favourablly for the Infernal Puppet.

I could possibly lose 100 victory points for no gain?