The "bursts" created by the shard of laputa while it's working can pass through the mana prism. The beam then changes into a mana burst, and the block associated with it seems to be destroyed permanently.

I tried trapping the burst in a tiny planet, and it took around 40 seconds to dissipate.

Running:
Botania 213, shadowbeam fork out of Eclipse workspace
Forge 10.13.4.1448