In Hoard there is a new achievement:
Fireth of July - Cause 20 groups of fireworks to go off in a Hoard Mode level
but I have no idea how to get it, it seems ridiculously hard. Do you have some suggestions to succeed?
Fireworks are triggered when a knight returns a princess to a castle. This means you kill a carriage and don't take the princess.
I used the first HOARD level, because it has the longest expected goal times (so they must expect you to survive longer). I started out each round by killing as many towns as possible, and keeping the archer count down afterwards. Towns give you a nice initial gold boost.
Whenever a magic tower springs up early on, killing it will give you lots of gold (and likely upgrade your dragon). They're also the most annoying thing on the map late-game (second being archers).
Make sure to use powerups - they're great for picking off groups of knights and individual magic towers. As for archers, you can run by them and not die as long as you don't stop.
Once you're good at simply surviving, you have two secondary goals:
It took about a six minute round to get the achievement, after about 45 minutes of practice (and the game was fun enough I didn't mind the practice). When it gets that far into the game, you'll start seeing two or three carriages together you can kill for fireworks.
For the achievement Fireth of July you need 20 princesses to be rescued and returned to a castle by a knight. Each rescued princess sets off a firework at the castle.
You can get some tactics and tipps from this video:
There's also a bug(?)/trick you can try to use on the first Hoard map, as explained by YouTube user Stormtempte:
There is now a fireworks cart that will travel the same way as a commodity (straw) cart.
When destroyed, the fireworks go off.
(If you are close to the cart when the fireworks go off, you will receive damage)