while the dmg to undead is in general worthless for this bomb there are sometimes you will see yourself trying to kill zombies with your bomb while freezing them (ie your team at vanaduke sucks so much you are left with both vana and most of the zombies yet you arent angered enough to release the lock and have them killed), so its a small bonus :)

I suggest you follow the ah, there was a ctr high on sale last I checked