FAIR WARNING: Marik has 3 Des Gradius not 2 (and maybe only 1 Lord Poison??), so if RNG listed you as naughty, he will tribute 1 DG to summon another and take control of you farming card using Mask of Remnants, hence you'll be doomed if you're using Labyrinth Builder or Cerberus farm (but I think it only happens like <10% of the time, so just keep farming). Ciao
I can confirm this. He uses his mask to take control of my Unhappy Girl or my Cerberus. But as he said, it happens <10% of the time. I can not figure out what triggers him to do so.
Yami Marik will always trubutes his DG with another DG if taking control of your card will make him enable to win within the same turn. I have lost 10 games at least so far because of that... ^^"
For Unhappy Girl's deck, he always tribute for another Des if the girl ALREADY atk him. For Lab, it never happened to me YET. Thus, I think the trigger is when Des is disabled (cannot change position, atk, whatsoever)