Question Question on summoning

I have been delving into summoning now.
Have it worked out that I can make new summoning spells no problem.

Now here is the question I am wrestling with.

I want to set a duration on some of them. For example, I made a spiritual hammer spell and I used summoning for ease to make it. So along comes mr spiritual hammer, no problem.
Is there a way to put a duration on it so that after X ticks it goes away? Or am I missing that little piece in the rest of the summoning code. Also wondering if a random summon can be done?
Like say Find Familiar and it summons a random list of mobs.

I bet this one is fairly simple and I just can't see it as usual.

Just add a trigger with

%wait% <some time>
%purge% %self%

You could do more complicated things, like setting the GET_OBJ_TIMER() on the object when summoning and then checking in the script:

if %self.timer% < 10
%purge% %self%
end

I used a MOB for the Spiritual Hammer. Not sure how I would go about making an obj that would independently attack and help the character. Or if it is possible.

Ah, didn't consider that. I don't think there's a good option for scripting this, then.

I tried doing a standard
af.duration = X
but that didn't seem to work.

maybe in the long run the players who MIGHT be on for hours could find it a little broken but probably for the average player, it wouldn't be an issue for game balance.

Why I am worried about this, I am not sure as my mud will never see the light of day. Only a few snippets I come up with and such and flesh out with help.