This card is actually very useful in certain situations. As you might know, creatures do not attack your base if the previous wave is still alive in PvE. By using Lost Banestone's ability, you can permanently paralyze a unit, as long as the building isn't destroyed. You're able to paralyze a wave of enemies, which will not cause any more to attack your base, making it easier on you. This video shows you Lost Banestone in action: https://www.youtube.com/watch?v=ebNr3BFd2E8 (7:05) Treim and Pritstift used Nomads *Green* instead of Banestone to make sure no more waves spawn, by keeping the first wave alive: https://www.youtube.com/watch?v=g52hVdIKqq4 You can see that not only Lost Banestone can achieve this.