|Spermy The Cat|
Something I thought of yesterday. Some spells have different casting times. Cure Light Wounds is a standard, as is most things. You get punched trying to cast it, you have to make a concentration check to make it go through. Some spells have a swift action, like Blood Money, letting you ignore getting punched. Then there's a full-turn action.
So the Druid casts Summon Monster III, which finishes after the start of his next turn. What happens if someone shot him on their turn, or someone punched him, before his next turn? Does he have to make a concentration check each time as the DM sends every NPC he has on hand to avoid flooding the field with cyclopes, or is he free to cast without fear?
Yup, 1 round casting time means smart enemies will do everything in their power to interrupt any creature who starts casting and doesn't finish in the same action. Hopefully you have some means of preventing the opposition from harming you during that round of casting.
Since you're talking about cyclopes: My druid uses fickle winds, wind wall and control winds to keep ranged attacks at bay, among other things. Flying (via wild shape or other effects) prevents melee attacks from ground-based opposition. Wall of thorns, entangle-type spells, and some domain spells are good for controlling a ground-based battlefield for times when flying is insufficient or impractical. And, of course, the front line does their best to get in the enemy's collective face, making it costly for them to attempt to go around to get to me as I'm casting.
The best approach, of course, is to summon while they enemy doesn't know you're there yet--either before combat or while you're still in the back around a corner or something.