Source: Wolfsbane

Horus charged, propelling the many tonnes of his adapted Terminator plate into a thunderous run with ease. His giant maul
 he held high overhead, ready to strike . Russ met the blow with a double-handed block, taking the mauls head on the
blade of his spear. A shock wave of empyrical energy blasted outwards, knocking nearby Space Marines over and tumbling head over heels.
Horus struck again, and Russ staggered back.