The canon is Hibiki's Magic, a setting in which all magic requires some sort of sacrifice to cast (usually the own user's life, soul, voice, time, memories, etc.) and largely deals with the consequences of using these spells, as well as how the characters inevitably try (and/or fail) to cope with any and all potential trauma that comes afterwards. It mostly aims for bittersweet stories, but many of the backstories that lead to it involve things like very young children being experimented on (as well as outright turned into monsters due to said experimentation), the overall aftermath of war, misguided attempts at coping with the deaths of loved ones, and so on.

Asuma here is a student studying magic himself, although his story is more specifically about him watching his friend descend into madness as he pushes himself to research despite his own magic causing his brain cells to deteriorate with each spell. So... while he hasn't seen death up close, Asuma does have a personal understanding of the weight that comes with magic, which quite frankly can (and often will) lead to the death of the user.