Cobwebs can be broken similar to wooden planks with mage fireballs

[GiacamoS]

This bug includes those placed by builder LimeeFox who was helpful for the demonstration...
You have to hit a solid block next to cobwebs as fireballs pass right through them normally...

[youtube]rXR18EMo4-4[/youtube]

Edit: This can be a bit weird sometimes as shown in video but it does happen...

 

[sjoerdtim]

Will look into this today if I have time.

 

[sjoerdtim]

Solved