Hyper Mt.Moonspell Achievement in Vampire Survivors

Like all bosses in the game, this one shows up at the 25 minute mark. Also like all other bosses, this one just hangs out and tries to chase after you slowly, so you just need to whittle its health down and kill it. Nothing special here - just get a solid build together (you should be well versed after the base game, and have the strongest characters and weapons unlocked) and survive until the 25 minute mark, and you should be able to lay waste to the boss very quickly.