What u need: high level riflemen, and razorbacks outfitted with concussion.
Attack with riflemen escorting the custom razors. May lose a few riflemen, but the custom razors will stun the bunker, and the bunker will be destroyed with minimal damage to your units.
Hope this helps
(Death Metal Playing In The Background)
War Commander: Level 43
Vega Conflict: Level 65
Battle Pirates: Who cares?