#420 is from the 24-man raid. And that has its own problems, as far as getting the card. At least 3 show up in the loot list every time.

If they mean #405, I don't believe it drops in the new Ex3. The same way Meteion didn't drop in Endsinger's Aria, which is the Ex version of Final Day where the card does drop. SE is fairly formulaic on this sort of stuff.