You can now limit the number of types of block a player can place, as well as limiting the number of blocks they can merge into it.
To enable this feature, enter the following into the block configuration:
max_merge: <number>
max_blocks: <number>
For example, if you wanted a maximum of 3 City blocks to be merged into a City block (plus the original block), you'd enter:
max_merge: 3
into the Blocks\city.yml file.
Or if you wanted to allow only 2 city fields per player, you'd enter
max_blocks: 2
into the Blocks\city.yml file.
Please note that a merged block does NOT count towards the maximum number of blocks. So if you limited a city to 3 merge fields (plus original block) and 2 city blocks - the player could potentially have up to 8 (2 x 4 merged together)
Please let me know if you have any questions or concerns!