Dwarves only have a hard time when they do not have any Artifacts that grant Paralysation or Petrification.

At the higher levels though, they can push the CGuardian around due to the sheer amount of Booster Spells that they have.

Chant of Fortitude + Ice Shield = 43% Armour
Banner of Fortitude = 63% Armour

If you are a Mage Lord, you can max out with the level 5 spell that grants an additional 33% Armour.

A Staff of Holy Armor can give another 20%.

Then there are the potions... ...

90 Armour is just about necessary for the Mountain Clans. What is equally important though, is the Damage.

This is my setup to deal with CGuardians.

King's Guard
Rune Master
Son of Ymir
Forge Guardian
Forge Guardian

Under RotE, the damage cap for the King's Guard is 400, so this translate into 40 Damage to the CGuardian. The Rune Master can attack twice, so that means 60 Damage. The Son of Ymir deals 65, due to its' additional Frostbite Damage. The Forge Guardians deal 30 Damage each.

Ergo, for the first round, you deal 190 Damage and 225 Damage for each subsequent round. The CGuardian will be toast in 5-6 rounds, depending on whether it is blocked by a frontline.

6 rounds mean 180 Damage by the CGuardian to your party. If you level up your Forge Guardian twice more each(so that they will have 185HP), nobody dies. ;) Given that they only need 1100XP to level up, this should be accomplished relatively easy while you level up your Dwarf to a Rune Master.