During the match, my [Gastal Thrillseeker] was stolen by opponent's [Possession Engine]. Because he didn't have max speed, so [Gastal Thrillseeker] didn't have deathtouch. However, after I destroyed his [Possession Engine] and gained control of [Gastal Thrillseeker] again, the creature still didn't have max speed ability although I had max speed at that time. It didn't have deathtouch so I lost the match finally. I think this is absolutely a bug