How to kill unearthed rampager

I see sometimes by expedtions the unearthed rampager, and this monsters resist elemental damage and chaos damage. i see no possibility to kill these monsters. What can I do than run away?

If they are immune to elemental and chaos damage, use physical. If they only resist the damage, dish out more. This league is intended for you to be unable to kill everything with most builds. PoEDB shows them as only having 40% cold resistance. Everything else is presumably map mods.