Atacked with a Loyal Cathar enchanted with a Hyena Umbra and a Lagona-Band Trailblazer also enchanted with a Hyena Umbra.

The opponent blocked with a Fume Spitter and a Llanowar Visionary

Actual: The damage of my loyal cathar resolved first, before Lagoona, triggering the Fume Spitter hability before Lagona's damage resolves.

Expected: both Cathar and Lagona damage should resolve at the same time killing both creatures and triggering Fume Spitter hability after the damage step resolves.