The lime wool blocks represent the blocks that will be placed in the lower corners of the pillars, and the blue wool blocks represent the blocks that will be placed on the top of the pillars. These blocks will change depending on the boss you want to summon.
1. Place down a chiseled quartz block. This will be the center of your altar.
2. Place purpur blocks on the 4 sides of the chiseled quartz block.
3. Place coal blocks in the spaces touching the purpur blocks so you have 3x3 platform.
4. Place quartz stairs around the platform against the purpur and coal blocks. The corners should be left open.
5. The lime wool represents the blocks needed to be placed in the lower corners of the pillars. These blocks will change depending on the boss you want to summon. These 4 blocks should be placed in the open corners between the stairs forming a 5x5 platform. (Type "/trigger help" to see what blocks you will need for a specific boss).
6. Place quartz pillars on top of the lower corner blocks (the lime wool or block you are using for a specific boss).
7. Place quartz bricks on top of the quartz pillars.
8. Place 4 more quartz pillars on top of the quartz bricks.
The blue wool represents the blocks needed to be placed on top of the pillars. These blocks will change depending on the boss you want to summon. These 4 blocks should be placed on top of the pillars making them 5 blocks tall in total (lime wool to blue wool). (Type "/trigger help" to see what blocks you will need for a specific boss).