Hypersmurf
Moderatarrrrh...
True, but a DM who doesn't allow a reflex save or require a to hit roll for a tactic like that deserves to have his dragons die.
Has he ever used the same tactic on you? If not, then he also deserves to have his dragons die.
I must confess, that was a generic "we" - I'm not involved in any games at present with mages high enough to act Wall of Force, let alone Summon Monster IX

I just have an image of an Elder Elemental doing a "bomb" into a swimming pool... Iron Giant style...

-Hyp.