Complex sentence: Dwarf Ironbreakers are the guardians of the lower deeps of dwarf holds, they are experienced tunnel fighters and often fight against Skaven and goblins attempting to tunnel into a Dwarf hold, without their efforts most dwarf holds would have almost certainly fallen to enemy attacks.
Split into simpler sentences: Dwarf Ironbreakers are the guardians of the lower deeps of dwarf holds, they are experienced tunnel fighters and often fight against Skaven and goblins attempting to tunnel into a Dwarf hold. Without their efforts most dwarf holds would have almost certainly fallen to enemy attacks.