In addition to killing the minions of hell in The Haunted: Hells Reach, many various environmental effects also occur during the maps you play.
To avoid an environmental effect, a player must destroy a Chronostone. Effects that do damage can also kill minions, as well.
Flies[]
Flies is the environmental effect of Night Frontier. Large groups of flies will roam the map, damaging any players caught in their path.
Meteor Shower[]
Meteor Shower is the environmental effect of the Lost Temple map. Meteors will rain from the sky, dealing direct damage and setting fire to anything they hit.
Collapse[]
Collapse is the Environmental Effect of the Abandoned Mine map. The mine itself starts to collapse, dropping heavy boulders from the ceiling. The boulders deal high damage but can be completely avoided by remaining outside the mine during the entire event. The screen will also have a more red color.
Fog[]
Fog is the Environmental Effect of the Stronghold. The map will have a thick fog that severely hinders visiblity, allowing enemy minions to close the distance unnoticed.
Lightning Storm[]
The Lightning Storm is the Environmental Effect of the Forsaken Canyon map.
Upon triggering, the whole light level will drop, as well clouds will form on the sky. After a short windup period, thunderbolts will start to strike at random locations of the map. These bolts can hurt both, human players and their enemies, causing mediocre damage and stun effects.
Given the low chance to be a hit by a thunderbolt, and "only" receiving damage and a short stun if hit, players can safely discard a Lightning Storm event as a ignorable nuisance and do not need to take special defensive actions.
Tornadoes[]
Tornadoes is the Environmental Effect of the Excavation map. Tornadoes will appear randomly and deal small, continuous damage to whoever or whatever is standing near them. The tornadoes will also slowly cause enemies to become enraged.
Acid Rain[]
Acid Rain is the Environmental Effect of the Steel Town map.
The sky and the whole ambient lighting will turn greenish and near instantly all outside areas will be hit by green rain. Any players being outside for a few seconds will start to take periodical damage and emit a poison-dust effect.
Since the effect will be applied to all people outside and deal considerable damage over time, it's highly suggested to seek shelter within one of the many buildings for the time the event stays in effect. It's possible to sprint from cover to cover without taking serious damage, but shouldn't be done unless to grab something or to switch to a better defense location.
Fire Eruptions[]
Pillars of fire on Museum
Fire Eruptions are the Environmental Effect of the Museum map.
Spirals of fire will erupt from the ground. Small rings will appear on the ground for a second or two before fire shoots out of them. Be sure to dodge accordingly when running around.
Warlock Hell[]
Warlock Hell is the Environmental Effect of the Island DLC map.
Huge balls of fire will appear from the lighthouse aiming for random positions on the map. When the ball hits the ground a warlock will appear.
Dangerous Fog[]
Dangerous Fog is the Environmental Effect of The Fog DLC map.
Like Stronghold, the map will have a thick fog that severely hinders visiblity, allowing enemy minions to close the distance unnoticed. BUT, there's a special fog roaming around the map that stunnes and deals a huge amount of damage to nearby players. Also this type of Fog converts normal enemies into raged enemies.
Ice storm[]
Ice storm is the Environmental Effect of Santa Town map.
Fog will increase to the point where it affects the player view. Given the strength of the storm it also makes the player move slowly.