darkness and fire pendulums I suppose? also the rules said " No more than 3 copies of any card in your deck besides pillars and pendulums" and you got 6 marks and out of interest do marks abide to the 6 only limit?
They do. You can only use 6 in a deck. By that logic, 3 would be max in this event. But by function, I don't see a problem with allowing six. Mechanically, they work just like pillars, after all. Earthquakes were no game-breakers in this tourny anyway.