The Dark Below

"'Under the surface in these ancient ruins, a darkness grows and beckons. They are libraries of forgotten lore and forbidden dark arts... once sealed away but now open once again with the reign of the Prince of Darkness. Some of the newer scholars of this archive who once embraced the dark arts have old grudges with the Prince and wish to help us... but he knows we are after him now, and a great evil approaches...' -Stage Description"

The Dark Below, or Stage 2-S, is the second Boss stage in Bloons TD 7: Dark Times. It is the Boss stage of the Bone Weaver, and upon this mission's completion, Act III: A Light in the Dark, is unlocked to the player. The Dark Below has 40 rounds, with the Bone Weaver fought on Round 40.

Track
The track is out in the open, at nighttime. Bloons spawn from a spiral staircase coming up from under the ground and leading to a large elevated stone platform ringed in three layers of steps. This platform is a part of a large stone pavilion, with columns rising from its corners and making way for a triangular stone roof. When bloons disperse onto the three tracks, every third bloon will go down each of the tracks, which make thick rushes less plentiful since they're constantly being divided among the three.

From this center platform and down the stairs, three trails marked with cobblestone path extend. One of them sticks out of the left side of the pavilion, and begins curving back and forth. Some of the grass between the curves are marked with desecrated stone pillars, preventing tower placement unless removed for $500. In one of the circles formed by the waving track, a Dark Mage stands atop a circular stone platform.

The second path comes from the top side of the central platform, curving left wildly before looping back to the right, and then going back in the middle in line with the center of the pavilion, going straight up in a line to the end of the screen. A second Dark Mage pedestal sits at the second large curve in this path. In the first curve, a removable pillar sits.

The third path comes from the right side of the center platform, making a large detour down, curving back up around a line of three pillars and some rubble that can be removed for $1000. Once back up to the center-right, the track swerves back and forth rigidly, before shooting in a straight line to the lower-right of the screen.

It should be noted that once the second phase of the boss fight begins, the entrance becomes the exit, and the exits will SPAWN the enemies moving toward the center.

Light and Dark
The Dark Below is done in a nighttime setting, meaning it is dark out. Certain lanterns release a small amount of light. The center platform shines with light that extends a ways out of the center, and some of the pillars have lanterns hanging on them that generate light as well. Each of the Dark Mage platforms also release a fair amount of light. Some lanterns dot the map, and can be lit for $100.

Towers placed in darkness will have their range cut in half and their attack accuracy reduced significantly, so maximizing on lantern location is key. Be careful not to bunch up towers too many though, as a boss fight with the Bone Weaver lay at the end of this mission, and attacks such as Ground Pound, Bone Claw, and Green Flare will devastate a super centralized defense. It should be noted, due to this, that the Bone Weaver does generate light itself (what with the glowing green magic inside of it), so if towers just so happen to be in the dark for some reason when the second half of the fight begins, his walking down the track does allow him to be seen.

Rounds
Not yet available

Additional Notes

 * The name fits well, considering a dark library below the surface is the key object of this mission. Not to mention the Dark Mages, use of a light and dark mechanic, and many other things.
 * With the help of the Dark Mages, the mission and especially the battle with the Bone Weaver, become a lot easier.
 * Somewhat inspired by Cursed Treasure 2's night time mechanic, where the gems you're defending and the towers generate light but cannot be placed in the darkness. This obviously somewhat modifies this mechanic however.
 * The mission rewards access to Act III, and provides 1000 MM in the form of the Bone Weaver defeat achievement.