And people were concerned about the treasures from the Brass dragon? Realistically, there's a very real chance of drawing in the bottom quartile about 25% of the time so it's quite possible that it's not great mana value vs. an X draw spell, there will be players who want the certainty of that. But, for some players, this could be fun.
And that's totally reasonable, or Elvish Piper. There are lots of ways to cheat this into play. But there are also lots of other things to cheat into play. I mean, do you cheat this in or Consecrated Sphinx ? They are both valid options but my vote is for the Sphinx.
Edit: But for those who do want to go the Sneak Attack route, yes this is obviously a better choice.
As a non-D&D player who is not into the lore, it disturbs me these personality-less non-legendary creatures get the "Elder" typeline.
Lore has less to do here as it does general rules of D&D being placed. Ancient is the 3rd oldest age a dragon can be (in this case 801-1000 years, taken from the Draconomicon that I had to pull off my shelf). I'd call that Elder, personally, but making them the oldest age a dragon can be, Great Wyrm, would have been better to represent that, but it doesn't flow off the tongue as well as Ancient does.
I don't know if the ages have changed in further editions, this is based on the 3.5 rules.