Underground

Underground
Lanes	4
Enemies
Difficulties
Easy	28,051%
Medium	65,680%
Hard	660,921%
Insane	41.84 M% (4.184e7%)
Nightmare	36.06 B% (3.606e10%)
Impossible	82.53 Qa% (8.253e16%)

Underground is the fourth region in the game, unlocked after completing wave 100 on Winter.

Completing wave 100 in this region unlocks the Volcano region.

Environmental Effects

This area has no environmental effects.

Challenges

Name	Enemies	Goals	Rules	Rewards
Level #1		Reach wave 250	Rules Max. 7 modules in total Max 3 defensive modules No ultimate modules Modules have to be maxed T1 or above Modules will be set to maxed T1 Enemies divide damage based on the wave they spawned in	+1% earth resistance per completed challenge
Level #2		Reach wave 500	Rules Max. 10 modules in total Max. 2 offensive modules Max. 2 ultimate modules Modules have to be maxed T2 or above Modules will be set to maxed T2 Darkness enemies deal additionally 10% of the tower's current shield and current health on every attack	+3% earth damage per completed challenge
Level #3		Reach wave 125	Rules Max. 10 modules in total No ultimate modules No utility modules Modules have to be maxed T3 or above Modules will be set to maxed T3 Enemies only take 100% damage from their own element type Enemies are immune to any other element type damage except for their own	Aftershock
Level #4		Reach wave 100	Rules Max. 10 modules in total No ultimate modules Modules have to be maxed T4 or above Modules will be set to maxed T4 Destroying fire enemies damages the tower for 33% of its max. health as fire damage (ignores shield) Destroying light enemies damages the tower for 33% of its max. shield as light damage Destroying earth enemies reduces the current energy of the tower by 33%	Tremors
Level #5		Reach wave 125	Rules Max. 15 modules in total Max. 4 defensive modules No ultimate modules Modules have to be maxed T5 or above Modules will be set to maxed T5 Enemies apply poison when attacking Poison reduces nature resistance and damage based on max. hp Higher stacks of poison are more potent	Poison Sting
Level #6		Reach wave 75	Rules Max. 8 modules in total Max. 3 defensive modules Max. 3 ultimate modules Modules have to be maxed T5 or above Modules will be set to maxed T5 Enemies are invisible and untargetable Enemies become visible and targetable for 0.25 sec. after attacking	Underground Gift

Modules

See also: Modules

Type	Name	Unlock Condition
	Soul Harvesting	Random 0.1%
	Darkness Armor	Random 5%
	Air Armor	Random 5%
	Earth Armor	Random 5%
	Nature Armor	Random 5%
	Shelter	Random 1%
	Transmute	Random 0.5%
	Offensive Pack	Random 2%
	Defensive Pack	Random 2%

Town Assets

The following town assets are unlocked after completing wave 100:

Minecart Minecart

Mushroom Mushroom

Rail Rail