on connect, players will choose class that will give benefits to nearby team-mates, and special ability that is bound to key

scout special - makes nearby enemies icons visible through wall

defender special - spawn static shield that blocks enemy shots (or block all shots in 1 way)

warrior special - rise weapons refire rate by 25% for him and team-mates nearby for 10 seconds

engineer special - builds mg turret (maybe building next turret nearby upgrade it)

spy special - short distance teleport

saboteur special - plant detonation pack, that do 200dmg in large area (timed or remote )

commander special - revive team-mates in close area with 50hp

marksman special - freeze enemy movement for 3 second (player dont stop suddenly but have bloced WSAD buttons so it wont break prediction)

medic special - shots orb that will sit inside team-mate and heal him on damage 75hp and jump to next team-mate, it will heal 3 team-mates and disappear (maybe charging that ball for 3 second could shot healing bomb that heals team-mates in area )
special is ability that you can use after pressing button, you will be able to use it once 30 sec or once / minute or maybe different specials will get different refire times
maximum 2 auras of same type should be allowed and they should stack so for example 2 spies with all team-mates near will give 90% transparency but 3rd spy wont make them 100% invisible
all of these abilities should be scaled by number of players so in 32ppl server it will be still playable
players should not get own benefits, they will give them only to others
it might need some more clever range checking than x units from player so big group wont need to stick tight together, maybe each teammate in group increase range of auras or some kind of chain like <[A Chain Of Hookers]> where each link carry on auras of eachother link

if there will be interest and some coder will want it to happen, I will start making icons for classes and some particle fx for each aura :]
hud concept

here are icons for this mutator,they might need to be converted into sp2 but its linux only tool, you can find converter inside nexuiz/data/models/sprites/ (if you dont have it then its inside data.pk3 at same path)
http://www.mediafire.com/?8iwx8dnppmk