The turn uses a combination of Arcane Missiles, Velen’s Chosen, Prophet Velen, and Ice Block to produce the hundreds of thousands of automated damage-dealing strikes without eliminating the second player. Until the next turn, that is, which should happen sometime on March 25th. You can watch the turn in progress live on Twitch.
[Source: PC Gamer, Twitch]
By setting up a chain reaction of around 240,000 arcane missiles targeting a player who cannot be killed at the moment, two players have engineered a Hearthstone turn that is currently running and will last approximately 40 hours and will hopefully net them a Guinness World Record.