I've fragged Echinophyllia a few different ways.
If the skeleton is thin enough, a razor blade is all you need.
If the skeleton is really thick, a dremel with a diamond cutting wheel works good.
I've also used a hammer and chisel with great success.
Here's a few pics of fragging Echinophyllia.
A thin Echinophyllia fragged with a razor blade. If you look closely at the coral, you can see lines or ridges flowing towards the center of the coral. A razor blade slide through those ridges very easily. It's cutting across the ridges (against the grain) that's hard.
Here's the first attempt.
The second attempt.
Chisel and hammer technique.
4" cold Chisel from Harbor freight(4.00)
Just give it a good whack on a hard flat surface.
Use a razor blade to separate the flesh. Don't rip/tear it.
Once the larger piece is separated, you can cut it into smaller frags.