Singularity, a level tool by Serpentine Widgets.

The Singularity is a triggerable object you can put into your level to make things more interesting.

When triggered, the singularity turns on for a specified amount of time, and then turns back off.  While on it will attract (like a black hole) all players who are within the defined radius.  Options for whom is to be sucked in includes "All players" "Only players who have powerups (boots, armor, shieldbelt, UDamage, Inviso)" or "All players with powerups, plus anybody with a Redeemer"

When a player makes contact with the singularity, a specified amount of damage is inflicted to him.  The default is 800, which is instant gibs.

There are sounds for activation (one shot) and "turned on" (can be looping) which can be defined for the effect you desire.

When activated, the singularity becomes visible, and then invisible again when deactivated.  As a default, it displays as a lens flare.  Change the display properties if you prefer something else.  Adventurous level designers could even assign a custom-built 3-d vortex mesh to this.

Magnetic/GravBoots, a pickup included with this package, can be put into your level.  You will find them under the AntiGravBoots in classes.  They work like the AntiGrav boots except they make you not able to jump.  Any player who possesses this item will not be affected by the Singularities or ChainedSingularities.

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In addition to a simple singularity, several "ChainedSingularity" objects can be put into a level and all set to the same tag.  When this event is triggered, one of the chained singularities (the one with the lowest number that can see that player) will pull players toward itself.  This can be used to create more complex effects, such as a space station that undergoes decompression every time the airlock is opened.  Instead of having all players pulled in a straight line toward one center of gravity (where those not in sight of the center would only be stuck against a wall) they can be pulled along a route toward wherever you want them to go.  This is similar to setting up path nodes or interpolation points (quite easy)

(NOTE: Chained Singularities are not guaranteed to work in version 1.00.  I think they will work, but I haven't fully tested them... If not, a new release of this package (1.10) will be out shortly.  If you want to use them, please make sure they work properly in multiplayer games before distributing your map.)

The sample map that comes with the singularity kit demonstrates the effect of this.  If you want to see the sample, please download the level editor's version at:

http://people.ce.mediaone.net/serpwidgets/UT.html