Odin's got the right idea. mwahahahaha
Yes, it was intended to be a tank destroyer.
CuCN is right, the amount of HP depleted is not based on the MAX, and changes with the current HP left. (I should note that...)
However, I could tweak it to where the MAX is depleted like a Shard of Void...but I have a feeling people would yell OP before anything else.