Battle, by 
A really lovely take on a more eveningy Lapper Festive, though obviously I come in with a lot of positive bias for the tileset. The background does not work at any window height other than 600, but otherwise everything looks great here. The alternate-color ornaments work well, not too garish, and everything else tiles properly. The use of tinting to mark non-solid giftboxes and other elements is good here. This isn't the most detailed account of the visuals but just, um, it all works)? Everything in the tileset is put to its proper use and flows together nicely without ever becoming distracting.
I will jump right in and say that I'm not thrilled with the nail gun usage here. The gold standard for nail gun is still Illumination, with the different pickups and stuff you can access with them, and Jolly Battle isn't that. There is one specific area you get to using the nail gun, thoughtfully marked off with additional nail gun pickups, but the reward is… a nail gun powerup. This just raises the question. Also you can shoot the nail gun powerup with electro blaster instead. (This must be intentional, it's the only obvious place to use electro blaster in the whole map.) But the level also has an RF powerup, and most of the level is crowded enough with curved platforms that your nails are never going to go all that far.
There's also a toaster powerup which feels like it has a lot of support: fastfire scattered around the level, a few big springs, and of course thematic resonance. It's a bit blatant, using both Duo Bouncers and Spike Bomb right after they were both MLLE-ified in the same level, but I suppose there are reasonable places to use them both, spikes on the right side and bouncers in all the gentle curves that weave through the top/ left half. Firework doesn't work everywhere but it, too, has its good spots. Other the nail gun and the electro blaster, I think weapons are well chosen here.
The layout in general is a good mixture of close spaces, thin platforms, and open spaces, which keeps players entertained and also helps you keep track of where you are. A few minor visual landmarks are also included. The biggest point of interest is the full energy carrot, especially in a level with three other carrots, but I think it does work. Multiple weapons can be used to shoot it down (but not the nail gun!) and it takes long enough that you put yourself in a lot of danger, which is what you want to avoid if you have, say, 1 health and desperately need a full energy carrot. It's a good trap.