Fyi for folks that care. My understanding is that Caverns of Time packs will give you “CoT” (watermark) versions of the older cards, but not the version (watermark) from the original set. To get some of the diamond cards, you need to collect all the lengendaries of certain sets (e.g., Mean Streets for Patches, Uldum for Zephers, Kobolds for Zola). So, if you get any legendaries from CoT packs for those older sets, they will NOT count towards getting the diamond reward and you would need to craft a second version of any CoT legendaries you got (i.e., craft the original set (watermark) version instead of the the CoT version). This means that, to be efficient, you would want to craft/collect the original version (watermark) of all the legendaries before opening CoT packs. Same holds true if you want the “complete collection” achievements for those sets.
Would be nice if they pointed this out to people. I think the natural assumption is that if I get a Uldum legendary from a CoT pack, it counts in my Uldum collection… but my understanding is that it does not.