Complex sentence: However, reckless use of the Druid Sleep when one has been mortally wounded, can be catastrophic as witnessed with the rebel Druid Brona after the First War of the Races.
Split into simpler sentences: However, reckless use of the Druid Sleep can cause complications. Also, overuse when one has been mortally wounded can be catastrophic, as witnessed with the rebel Druid Brona after the First War of the Races.