That sucks to hear, Damon. I'm having the opposite problem where my PCs are rolling through everything with the greatest of ease. They cleared the entirety of the courtyard and upper floor of Renchurch in one go with little attrition, effectively using blanket immunity spells(mainly Death Ward and Freedom of Movement) to make most of the monsters incapable of hurting them, then using buffs like Good Hope and bardic music so that even if they do have to roll a saving throw, they need to only not roll a 1. I just finished the following encounter:
Nathalazzar and his two golems. While the whole team was ready with held actions to launch ranged attacks at the first person to enter, the resulting 80 points of damage did little with shield other splitting the damage between its target (scythe wielding paladin fighter) and the juiced up Oracle of life, who proceeded to Cure Critical him for most of the damage. Meanwhile, the Magus moved up, dropping a grease spell between the two golems, making them easily fall prone with little chance to regain their footing. The bard used bardic performance to juice up everyone's attack and damage while also healing the oracle of the split damage she had just taken.
Next round, the fighter and Dhampir close, dealing 90% of one of the Golem's health in damage. The golems get really lucky, hitting four times from prone on the fighter, which due to stoneskin and shield other score minimal damage. Nathalazar unloads on the fighter, knocking him prone with a force bomb and hitting again with acid. The fighter has about 25% of his health remaining, but is quickly brought to about 66% with channeled positive energy and cure spells.
Attacking from prone, the fighter still easily dispatches one golem and critically hits the second, reducing it to 5% of its health. Its quickly finishing off by the magus. Nathalzar tries to hit the in-cover oracle and misses twice (bad rolling). He is then flanked by the magus and fighter, who switch to magical bludgeoning weapons as they close while the oracle unloads a searing light on him for about 40 damage. Unable to escape the flank due to the fighter's Stand Still feat (and some other close quarter feat that keeps them from withdrawing), Nathalzzar dispatches a last ditch detonate, but its too late; the pair reduce him to dust in seconds.