A knife in the back!

In a river near a stone structure, a red-clad character named McKellen attacks a blue, winged character named Bambr (bot), who is surrounded by a glowing blue aura and is being chased by the red character. The red character, McKellen, moves from the left side of the screen toward the right, attacking the blue character, who is knocked back and eventually killed, as indicated by the on-screen text in Russian and the character's health bar depleting.