On this map infected mobs were expelled from the castle.
You have a small amount of potion that contains a cure for the infection. If you want to stay alive then you need to fend off the infected swarm and not let them steal the potion. If they manage to steal the potion, you lose and get infected.
version: 1.5.3, 1.5.1, 1.4.2, 1.4.1, 1.4.0, 1.2.13, 1.2.10, 1.2.9, 1.2.8, 1.2.7, 1.2.5, 1.2.3, 1.2.1