The blasting of the mineshaft played a significant role.
Continuing to read further,
[Skeleton Longbeard Warrior (Tier 5)], also a heavy infantry unit, is proficient in heavy armor and two-handed battle axes and has a charge skill in its abilities. It shares the same effect as the Tauren's [Frenzied Charge], knocking back enemies along the way and charging directly into the enemy ranks.
[Skeleton Dwarf Cavalry (Tier 6)], the dwarf's unicorns cavalry, skilled in riding, light armor, and saber.
It can ride unicorns, traveling quickly through forests and rugged mountain roads.
It also has its very unique characteristics.
[Skeleton Thunderous Gunner (Tier 7)]
[Faction: Undead]
[Racial Traits: Undead, Hollow Skeleton, Weakness to Light.]
[Skills: Precision Aiming, Rapid Reload, Thunderous Shot.]
[Innate Abilities: Intermediate Firearms Mastery.]