Plane Sailing
Astral Admin - Mwahahaha!
Don't forget the potential for divinations to warn the bad guys that something really big is coming down the pike at them. If they are facing enemies of that calibre, then you can expect the bad guys to be gating in friends of their own - and the bad guys are more likely to be selling their soul for bigger favours - e.g. very advanced pit fiends with wishes and such... allow the two summoned ultra-nasties to square off against one another and let the lesser mortals handle their own problems between them. (hint: take a look at the finale of (contacts) Temple of Elemental Evil storyhour for an excellent way in which this happens).
Another good option is that as soon as the Solar appears, all the evil guys bail out instantly. Solar looks around with nothing to do. Bad guys reform and come back later. Solar will eventually get angry if he is continually summoned away from his work and to this world.
Even better, make the summoning have consequences... What if that Solar was "holding the gate" for an entire plane against forces of evil at the point when he was summoned away! Maybe that plane falls to fiendish forces! Continual summoning of a Solar might have grave effects on battles out amongst the outer planes!
Also, as a DM the way that I would RP a Solar would be good in a terrifying intensity. I would have any cleric who summoned a Solar in this way completely terrified. The Solar wouldn't be a namby-pamby who fought the enemy with ultra-buff weapons and then gave them a lecture... No, it would expect conversion to its cause, it would judge all those present for *any* acts of non-good-ness. It would be working to a higher agenda than these mortals understood...
Another good option is that as soon as the Solar appears, all the evil guys bail out instantly. Solar looks around with nothing to do. Bad guys reform and come back later. Solar will eventually get angry if he is continually summoned away from his work and to this world.
Even better, make the summoning have consequences... What if that Solar was "holding the gate" for an entire plane against forces of evil at the point when he was summoned away! Maybe that plane falls to fiendish forces! Continual summoning of a Solar might have grave effects on battles out amongst the outer planes!
Also, as a DM the way that I would RP a Solar would be good in a terrifying intensity. I would have any cleric who summoned a Solar in this way completely terrified. The Solar wouldn't be a namby-pamby who fought the enemy with ultra-buff weapons and then gave them a lecture... No, it would expect conversion to its cause, it would judge all those present for *any* acts of non-good-ness. It would be working to a higher agenda than these mortals understood...