I must've dueled Chazz over 100 times now and I have 17 Armed Dragon LV10 and 12 VWXYZs but 0 Lindwurms. Is the drop rate for them bugged or something?
It was confirmed some time ago that drop rates are rigged to emphasize you playing more. That "having every card 50 times except for one, which you have none of" is how it always happens, with every event. It's kind of a deceitful practice, but it's just the way it is.