You can use with to manipulate any online player or NPC, I'll give some examples:
NPC Code:
if (playerchats) {
if (startswith(Jail player,#c)) with (getplayer(#e(12,-1,#c))
setlevel2 jail.nw,32,32;
}
Would jail the player with the account said after jail player.
NPC Code:
if (created||timeout) {
for (i=0;i<playerscount;i++) with (players[i]) {
playerx=32;
playery=32;
}
timeout=0.1;
}
Would warp all players in the level the NPC is in to 32,32
NPC Code:
putnpc2 32,32,{join Bomb;}
i=npcscount-1;
with (npcs[i]) setstring this.power,3;
Would set the this.power string of the recently placed NPC to 3.
Do keep in mind that I've never actually worked with any of this scripts so the things I've just said might be completely wrong.
Also it can only be done by serverside NPC's.