mords disjunction trap?

[fl8m]

I'm designing a dragons lair in my epic campaign and was considering having certain spells triggered as any non-collossal creature past by them. i was thinking of something simple starting with say a fireball then building up from there till the last one being mord's disjunction.
However i'm having trouble overcoming my own inner-rules lawyer. Is there a way to have a spell triggered like that?

 

[James McMurray]

I'm designing a dragons lair in my epic campaign and was considering having certain spells triggered as any non-collossal creature past by them. i was thinking of something simple starting with say a fireball then building up from there till the last one being mord's disjunction.
However i'm having trouble overcoming my own inner-rules lawyer. Is there a way to have a spell triggered like that?

I believe the 3.5 DMG and 3.0 Song and Silence both have fairly extensive rules for creating traps.