A good tip to avoid broken battens is that once you have hooked on to a nail you want to remove turn your slate rip from the downwards nail pulling position as far left or right as you can.
How to remove roof slates without breaking them.
If you are working on a large roofing project place a dumpster on the side of your house and toss all nails and shingles into this receptacle.
Removing shingles involves moving nails.
A slate hammer another important slate roofing tool has a hole punch at one end used to punch holes in slates for nailing.
This video from bunnings shows you how to take a tile off and replace it prop.
You do not want these nails to stay on the roof nor do you want to leave them scattered around your yard.
The tool required for removing slates from a roof is the slate ripper which is a sword like object that slides up under the slate and pulls out the two nails that hold it in place.
Working with roof tiles is a lot easier when you know a couple of basic tricks.