It’s waterproof, it won’t ignite in heat. You scrape it with a steel scraper which is often included, and it produces a big spark. You can also use the backside of your knife blade. No need to dull the sharp side!
You can ALSO scrape little shaving off of it, into a pile, and THEN scrape a spark into that little pile and it ignites with surprising ease. Forget about rubbing two sticks together, this is the tool to have. See this video demonstration shows just how easy it really is. In a survival situation, the last thing you need to be struggling with is rubbing two sticks together! It aint so easy to start a fire with two wooden sticks, most folks really couldn’t do it, they aren’t patient enough or skilled enough. The magnesium stick is like magic, you can even produce a spark in pouring rain supposedly.