Mobs and boss ideas

Maybe they can be different bosses which have been found in certain strongholds as well as needing to solve puzzles in order to unlock the portal to the boss As for the mobs perhaps they can be spirits of some players walking around your world but they behaviour is the same as the spiders they won't attack in the day but they will attack you at night and they only appear if it's a full moon or no moon and this is a hostile mob which will attack anything that has done any sort of evil deed within 50 blocks and it only hunts at night or in dark areas (nightwalker) but they can stopped if you trade with 3 different villagers (the trades has to be at master level) or placing 4 soul touch's around you Maybe some strongholds can have clues to where either the location of another stronghold or a ruin and sometimes fake clues and some strongholds without end portals Maybe you can do a boss which has the power to bring players back from the dead to use as minions to attack the player (similar to the necromancer's power bringing mindless minions back from the dead)