Can't believe I'm going to help
revolg...

I'm not sure if this will work, because I haven't tested it, but it should. Put this text in your script file:
CODE
illusions = {
["kelp"] = {"illusion 1",
"illusion 2",
},
["bloodroot"] = {"illusion 1",
"illusion 2",
},
} -- illusions
math.randomseed(os.time())
And this should be an alias. (Check the regular expressions checkbox)
CODE
Alias: ^\s*IL\s+([:alnum:]+)\s*$
Send:
if illusions["%1"] and #(illusions["%1"]) > 0 then
rand = math.random(#(illusions["%1"]))
Send(illusions["%1"][rand])
else
Note("No such illusion group")
end
It should be pretty obvious how to add new illusions and illusion groups in the script file.