Bosong Coldtree

Boss file · Sands of Time, Sand-3-B

Bosong Coldtree

At the end of the tree line, the famed cold tree gathers itself.

Residue... Resentment

Our snow and ice will not melt for a thousand autumns; our curse will be endless.

Lore

The cold trees met earlier now stand in a line. At the far end of that line, beyond the richly leafed cold trees, the famed cold tree gathers itself — Bosong Coldtree. Looks like we are meeting Coldtree squared. Hopefully not Coldtree to the tenth.

At the end, it says that your research buries their trees, and your clocks let their ice and snow pass away. Their snow and ice will not melt for a thousand autumns; their curse will be endless, endlessly difficult to sever. Compared with a normal zombie, it feels more like a piece of resentment left in the Sands of Time.

Mechanics

Role

Area miniboss · Cold-tree line core

  • Appears as the boss at the end of the cold-tree line.
  • Applies pressure through the tree line, tree summons, and field control.
  • Version 0.17m strengthened Bosong Coldtree on high difficulties: shorter startup, shorter summon interval at low health, and a higher summon cap.
  • Control active cold-tree count, save burst damage for exposed windows after landing, and avoid wasting damage into jumps or shell state.

Advanced mechanics

Bosong Coldtree expands the ordinary Pine Zombie's field compression into a boss loop. Startup timing, damage-triggered summoning, summon caps, jump relocation, and a compressed shell state divide the player's damage windows into several different kinds.

HP, startup, and summon gate

Bosong Coldtree's main-story form uses the same linear boss HP scale: Hmax = 2000(d + 5), where d is the difficulty index. Reinforced challenge contexts can add another 5000 HP; m in the formula marks whether that reinforcement is active. The important question is when the summon loop opens.

Normally, the first summon waits about 10000 − 2000d internal timer units, so higher difficulty starts earlier. If the player deals more than 1000 HP before that timer finishes, the summon condition is also satisfied early; heavy opening burst therefore brings cold-tree pressure forward.

Hmax⁡=2000(d+5)+5000m,Tstartup=10000−2000dH_{\max}=2000(d+5)+5000m,\qquad T_{\text{startup}}=10000-2000d
Either enough time or enough damage pushes the fight into the cold-tree summon loop.

Cold-tree cap and low-HP acceleration

Bosong Coldtree keeps summoning only while active cold trees remain below the cap. The cap rises with difficulty and can be read as Cmax = 2d + 2, which is why high difficulty fills the line more easily.

After each summon, the next summon timer is recalculated. Near full HP it is closer to the long interval; low HP pushes it toward the short end, and higher difficulty lowers that short end further. Version 0.17m's strengthening is mainly this combination of earlier startup, faster low-HP replacement, and a larger simultaneous cap.

Cmax⁡=2d+2,Tnext summon∈[150(11−d),3600]C_{\max}=2d+2,\qquad T_{\text{next summon}}\in[150(11-d),3600]
Reduce the active tree stock first, or the field stays trapped under a compressing tree line.

Jump, shell state, and damage windows

Bosong Coldtree relocates by jumping across the field. It does not take damage during travel, so spending one-use burst during the jump animation has poor return; the reliable damage window is after it lands and becomes exposed again.

In its compressed shell state, each positive hit is reduced to a small chip, roughly a 5 HP step. Sustained small damage can still push through shell time, but true burst is better saved for exposed windows. At the same time, active cold trees must be cleared or the summon cap stays occupied and the board remains compressed.

ΔHshell≈min⁡(5,H),ΔHjump=0\Delta H_{\text{shell}}\approx\min(5,H),\qquad \Delta H_{\text{jump}}=0
Use sustained damage to clear trees and save burst for exposed windows; jumping and shell time are poor dump points.