Okay, so.... Never thought I'd be saying anything negative about knight-enchanters, but tempest archers are much better dragon killers than knight-enchanters.
Well, maybe "better" isn't the right word, but they are certainly more efficient.
And awesome.
Like... ****ing awesome.
Harold and his go-to gang -- Cassandra, Blackwall and Vivienne -- jumped through all the hoops that Frederic the draconologist made them jump through, up to the point where they had to go back to Skyhold and research an ancient text. At Skyhold, I thought it over and decided that, instead of going right back to the Western Approach to take down the Abyssal High Dragon, I really, really wanted to get those last four shards in the Hinterlands, and this time I wouldn't be sneaky about it.
This time we would be dragonslayers. And the Fereldan Frostback was at the top of the list. A short while later we scratched her off the list. 
Holy crap. No one even died this time. And we only used 3 health potions.
We closed distance with her fairly quickly, running right past all the dragonlings in the way, and dodging all the fireballs she threw at us. Harold's Long Shot ability really shone here, and a couple Long Shots and one 'Thousand Cuts' later, we took her down to half-health fairly quickly. Cassie and Blackwall may have helped a little
... Vivienne kept barriers on us all like a champ, and when Frosty took off to her high hidey-hole, she played right into Harold's Long Shot hands.
And then the red templars showed up. 
The hell did they come from? 
We couldn't let them steal the glory, and possibly the loot, so we had to deal with them, and that's where we ended up using the three health potions, cuz Frosty took advantage of the distraction to cook us a little bit.
Didn't matter in the end. Soon the red templars were dealt with, and the dragonlings were dealt with, and shortly afterwards Frosty herself was dealt with. I'm still a little surprised at how quickly we took her down, after it took three tries in my first PT.
Added bonus:


Anyway, it was so much fun that we're gonna go do it again, out there in the Western Approach.
Oh yeah. The shards. Almost forgot. 