The problem with knowing and not knowing

So last game session we spent the entire time planning our next combat encounter.  We know it is going to be a wormskull horror with the potential for some adds if the gm is feeling vicious. We've setup a deadfall trap to potentially add some damage and surprise.  What we really need is an array of debuffs to apply to make the combat feel a little safer. What we have is a pair of glass cannons in the form of an archer and a nethermancer a tank in the obsidiman warrior and myself filling out the middle with my weaponsmith/shaman (or as I've begun to think of him as the Iron Druid after the book series). I've got some utility spells, a mote of crowd control and defense, and some decent melee damage. I feel like it's not quite enough, but we'll probably manage with only one or two deaths... I hope we still have enough last chance salves for everyone that will need one.