Invisi Blocks
This modification adds special invisible blocks to Minecraft that look like regular building materials but don't obstruct movement at all! Players and mobs can freely pass through them, creating interesting visual effects and optical illusions.
Currently, this functionality is available exclusively in creative mode. The unique feature of these blocks is that they automatically adapt to any textures - when you change texture packs, the appearance of the fake blocks will also change, maintaining complete visual integration with the environment.