Bastion

Bastions are blocks which allow you to secure an area from enemies. They generally come in two varieties: Vault Bastions and City Bastions. Depending on its type, bastions can prevent block placements, reinforcements, throwing ender pearls, and more from any player not on the Namelayer group the bastion is reinforced to. Bastions can be broken over time by performing many disallowed actions.

Bastions are managed by the Bastion plugin (source).

Creation
Bastions are created in a bastion Factory. Once you have the bastion block (typically a sponge block for vault bastions and a bone block for city bastions), place it and reinforce it to the desired Namelayer group. Any player on this namelayer group (TODO: with a certain nl group permission I think?) will be able to bypass the bastion's protection.

Note that due to the high creation cost of bastions, it makes little sense to reinforce them with anything other than diamond.

This means that, not including the 6 factories above, the total cost of a bastion factory is roughly 96 diamonds, 192 emeralds, 174 iron blocks, 57 gold blocks, 121 redstone blocks, 1024 ice, 1024 glass, 1024 charcoal, 512 lapis blocks, 512 obsidian, 512 chests, 512 grass blocks, 192 gunpowder, 96 slimeballs, 32 eyes of ender, and a lot of lava. Due to this steep price, many players produce bastions collaboratively or purchase them from others with the means.

Protection
Bastions cover a square area from the y level where the bastion block is located up to the sky limit of the world. This means it makes little sense to place bastions anywhere except bedrock. The exact radius of the area depends on the type of bastion.

Breaking
Each time an action forbidden by a bastion is taken within its area of protection, its reinforcement takes one break worth of damage. Once the reinforcement of a bastion reaches 0, the block is destroyed and its protections removed.

Bastion Cap
A Bastion Cap a layer of blocks (normally one layer of diamond reinforced obsidian) placed around the bastion block itself. Without a bastion cap, it may be more efficient for attackers to mine the bastion block itself rather than break it via block placements.

City Bastions
City bastions prevent block reinforcement, but do not prevent block placement or throwing ender pearls. City bastions generally have a radius of 50 blocks (so a 101x101 square, centered at the bastion block).

With a single player reinforcing blocks non-stop, city bastions take exactly 30 minutes to break.

50% of the damage dealt to city bastions will also be inflicted on all other bastions within a 25 blocks radius (center block + 25) from the city bastions which were not affected by the initial damage.

Vault Bastions
Vault bastions prevent block placement, block reinforcement, throwing ender pearls, piston extensions causing blocks to enter the bastion field, and liquids from flowing into the bastion field. Vault bastions will not block entities (including falling entities), dragon eggs teleporting into the bastion field, or bonemeal usage inside the bastion field.

Vault bastions generally have a radius of 20 blocks (so a 21x21 square, centered at the bastion block).

With a single player placing blocks non-stop, vault bastions take exactly 1 hour to break.

50% of the damage dealt to vault bastions will also be inflicted on all other bastions within a 5 blocks radius (center block + 5) from the vault bastions which were not affected by the initial damage.

Overlapping Fields


While it is efficient to spread bastions out, defensive structures make use of overlapping bastion fields to ensure breaking a single bastion won't grant the breaker access to a full 21*21 area. In open spaces, blocks placed in the overlap would be a liability (since both bastions would take full damage) but vaults use walls and other physical barriers to prevent attackers from doing so. Immense subdivision and traps make ground assaults against such a structure difficult.



One other form of field overlap involves the vertical dimension. You can protect an area in the sky (typically at sky limit, but not always) by forcing attackers to break one bastion at a time. This is achieved by separating bastion layers by 8 blocks (to prevent mining) and moving each successive layer one block diagonally away from the center. Unless they can find a way to place bastions closer to the center (either on the outside of your structure or on top of it) they can only break a single bastion layer at a time.

Block glitching
Vault bastions remove block placements, yet for a tick the block appears as normal. Server rules allow using block glitching to pillar out from holes. Block glitching more than a few blocks high is possible although timings make it difficult.

Exile glitching
Exile players are teleported outside of bastion fields. With a correct setup this can allow teleportation over large distances. This is against server rules.