Level 4 – The Labyrinth
Difficulty: Easy
Waves: 20
This level has a lot in common with the previous one – your key problem is making sure your innermost defenses gain experience fast enough that they can handle incoming Ninjas.
You should put a Crypt on the High Ground. It’s in close quarters, but the High Ground can only hit a narrow stretch of actual road, so Temples won’t be as useful. Flank the entrance to the Gem Cave itself with Dens.
Setting off Ninja smokebombs early is a challenge in this level. Both entrances are surrounded by snow – the first location where you can build a Temple is the second corner, in both cases. Build Temples as close as you can to the actual entrances, but place additional Temples on those corners as well – once upgraded to Burning Temples, they can cover a fairly wide area.
Level 5 – Plan B
Difficulty: Easy
Waves: 20
Once again, the main challenge on this level is training your innermost defenses. Crypts should go on the two southern High Grounds, while a Temple on the central High Ground can do a lot of damage and help against Ninjas. Don’t build too far forward too early, or you’ll starve your Crypts of experience.
Your enemies will target the western gem cave first, so you should focus your defenses there. Dens on the western ridge will provide some damage, and the eastern ridge has room for a sizable battery of crypts. Place a few token towers near the eastern cave to deter the AI, but if you’re playing well you shouldn’t need them.
Don’t forget to clear out the trees to the north and place a Den and Temple when you see a Ninja wave approaching. By that point, hopefully, your caves will be well-protected.
Level 6 – Enigma
Difficulty: Normal
Waves: 20
No High Ground on this level, but the islands in the road can hit a lot of targets, and they have the perfect terrain types for their positions – a Temple near the entrance and a Crypt near the gems. Unfortunately, they’re also covered in trees. In fact, the entire level is covered in trees. Nearly every strategically useful tile is completely covered in trees.
Cut Out is going to be very important on this level, so your first tower should be a Den on the one free mana well. You should also set up early Crypts on the handful of tree-less snow tiles near the gem cave, and a Temple on the one free ash tile near the entrance, because this level is going to throw Ninjas at you unfairly quickly.
Once those are taken care of, try to cap the other two mana wells as quickly as you can, then set up a Temple and Crypt on the islands.