During big fights in the arena or gladitorial ring between two well known or important warriors. When one looses and dies, the crowd throws copper coins into the arena for the slain warrior to take with them on their passage of death. This is to make their passage and afterlife richer and less troubled. It is a sign of respect.
Believable magic, like ordinary physicis, operates according to some invariable laws that always result in some kind of cost or "bounce back". The grater the magic, the more it should cost the character physically, emotionally, and spiritually.