Hyper Lake Foscari Achievement in Vampire Survivors

Like all standard bosses in the game, the boss of Lake Foscari shows up at the 25-minute mark, and is a deer with big antlers. When it first shows up, it seems to spend a good deal of time healing from the damage you do, while also moving very fast. Then, it'll start taking damage, and it's quite the tank. Thankfully, it has no attacks of its own that I ever observed, so just do circles around it until it's dead.