Mana benders are individuals who can impose their will on reality by altering it based on their perception, usually interpreted as "magical abilities". These powers can take a number of forms, including telekinesis, transmutation, matter manipulation, etc. Benders access their abilities by use of their Mana, which they access through concentration and focusing.
Benders have limited range and cannot affect what they don't perceive, and cannot impose their will on anything if they have no will to impose. Nevertheless, using their abilities has unintended consequences. These effects happen elsewhere, outside of the user's control, and are seemingly random. However, the strength of these effects depends on the power used by the bender. Say they transmuted a coffee maker into a toaster; the unrelated effects would be small, like a flock of birds dropping dead from the sky. Bringing the dead back to life would create a stronger effect, like an earthquake.
Since users have limited range and cannot create these strange happenings with their powers how is it that they happen indirectly?