Medusa vs Nyx Assassin

How this matchup plays

Burning through Medusa's mana is the same as burning through her health, and Mana Burn is designed to do exactly that. A single cast from Nyx Assassin strips away a huge portion of Medusa's effective HP by targeting the source of her Mana Shield. This isn't an inconvenience that stops her from casting a spell; it's a direct attack on her survivability. Vendetta lets Nyx get into position unseen, apply the burst, and either finish her or leave her completely vulnerable. It's a fundamental design counter.

This dynamic forces Medusa to play scared for the entire game. Any time she's farming a lane or the jungle alone, Nyx Assassin can appear, drain her mana, and put her in kill range for his team, even if he doesn't stick around. Medusa must rely on her team to provide constant vision and protection or rush an item like a Linken's Sphere, which delays her core damage items. This pressure severely restricts her ability to farm and hit her late-game timings.