Boulder Trap

The Boulder Trap deals considerable damage, often instakilling those whom it hits.
==Dungeon Keeper==
The Boulder Trap is potentially the most destructive trap available, first available to the player in Nevergrim. It allows the player to lay down a huge round rock which rolls over heroes and enemy creatures when they come within range. The trap requires a Workshop made up of at least 26 squares before it can be manufactured. Ninety-nine times out of a hundred, a Boulder trap will instakill any creature or hero whom it touches (except the Avatar, who is immune to this trap; if he gets hit by one, the Boulder will simply explode); it's rare, but not unheard of, for a creature to survive being hit by one (though (s)he'll still be considerably harmed).
The trap triggers when a hero or enemy creature comes within its line of sight. The Boulder then begins rolling towards them. Boulders always go left when they hit a fork at a straight angle (the manual and the Dungeon Keeper Premium guide book incorrectly state that Boulders go in a random direction at forksDungeon Keeper Gold Manual, p. 43.), therefore it is possible to predict its path. The Boulder is destroyed after a while. It is also weakened whenever it rolls over a creature - so it might be advisable to use multiple Boulder Traps when a large group of enemies tries to invade the dungeon.
Should the Boulder roll onto lava, it will explode, or disintegrate if it rolls into water. Although your own creatures do not set off the trap, they can still be squashed if caught in its path, so must be treated with extreme care. The player can activate the trap by slapping it, and can also redirect their own boulders if skilled enough. Note however that each slap will weaken the Boulder, causing it to break more quickly. If activated this way, the trap will disappear, so it cannot be sold any more and needs to be replaced with a new one.
One must be very careful when dealing with enemy Boulder traps. If one knows the enemy has the trap available, they should be very careful when breaking down doors or walking down corridors. When possible, move through suspicious areas using Imps or very fast creatures if one is more skilled to minimise damage and harmlessly activate them. If one is quick, they can place doors in any corridors and certain types of rooms to change the landscape such as Treasure Rooms (for their columns), Hatcheries (for their lowered floor) or Temples (for their raised floors). Note, however, that a Boulder trap will destroy any Guard Posts. If one is skilled enough at manipulating the environment and their enemies, it is possible to use the opponent's traps against them.
The trap will crumble after it has rolled over 10 units. In KeeperFX, however, some creatures weaken the Boulder more than others and the trap will kill fewer units as a result. Triggered Boulder traps can also be destroyed by Meteors and Grenades; however, creatures are not smart enough to think of shooting these weapons at moving boulders of their own accord. Boulder traps and Floating Spirits are completely unaffected by each other.
==Dungeon Keeper 2==
Boulders cause damage equal to half the health of the creature that it hits, and cause more damage to stunned creatures. If a creature gets hit by enough boulders, it will die. Boulders cause damage to your creatures as well as the enemies. Boulders will cause damage to Dungeon Hearts (yours will cause damage to your own) so can be used to take out enemy hearts. A Boulder's direction can be changed by slapping it, and it will bounce off any walls it hits as well, so beware of where you set them up. A Boulder takes damage from rolling. If you are using the patched version of the game, it takes damage from slaps and from hitting creatures as well.
Also known as the Sphere Trap.
==Dungeon Keeper Online==
In Dungeon Keeper Online, the Boulder Trap was very similar to its Dungeon Keeper counterpart, though some high-level units needed two Boulders to finish them.
==Dungeon Keeper Mobile==
===Overview===
Available once your Workshop reached level 5, the Boulder Trap flattened everything in its path, dealing considerable damage to everyone it hit. It was triggered when an enemy got within five tiles, and would continue to roll in a cardinal N/S/E/W direction until it collided with a wall.
The Boulder Trap was only available for use once before needing replacement. These traps were built instantly. Upgraded versions were expensive: If you paid 50k gold for the level 2 upgrade, subsequent rearms cost 25k gold.
===Notes===
*Single-use trap with no build time.
*Hidden until triggered.
*Rolled until it hits a wall.
*Effective against groups of minions.
Required Workshop (level 5).
===Stats===
Targets 	Ground
Damage Type 	Physical
Number of Targets	Unlimited
Attack Speed 	Single-Use
Attack Range 	Until Wall Collision
===Traps Available===
Workshop	Traps Added	Max Traps
Level 5 	1 	1
Level 6 	1 	2
Level 7 	1 	3
Level 8 	1 	4
Level 9 	1 	5
Level 10	1 	6
Level 16	1 	7
Level 18	1 	8
Level 24	2 	10
Level 27	2 	12
Level 34	1 	13
===Upgrades===
Level	Damage	Cost (Gold)	Rearm Cost (Gold)	Workshop Required
1 	280 	1,250 	1,250 	Level 5
2 	360 	50k 	25k 	Level 5
3 	540 	175k 	50k 	Level 9
4 	645 	2.5M 	75k 	Level 14
5 	755 	7.5M 	90k 	Level 20
6 	870 	15M 	? 	Level 24
7 	1215 	300
Dread
Stones	? 	Level 35
Special:
Large
Damage
Increase
==References==