KOTSS zombie defense

It'll be cool --- Just above the lower mists stands a once forgotten sky isle. It had been overlooked by the patrolling knights because it looked very harmless. However, a few years later, a Korblox Deathspeaker managed to summon a rift that led to this isle, just like they did with Ascendus. The Deathspeaker and his zombies managed to get through this rift and tried to corrupt the isle. Once the knights found out, they held back the incoming horde as best as possible and built a small base on the isle. However, the Deathspeaker escaped and hid somewhere on the isle. To this day the knights make sure the horde does not escape from the valley in which they come from, because if they do, the isle could be taken over and corrupted, which could spread throughout the skies.