The standard Magic Data Symbols are safe for anyone to use because they only read data. They don't update a concrete5 site's database.
The symbols in Black Magic Data are the bad boys. If used badly, some of the symbols in Black Magic Data can make controlled changes to the database or do other potentially dangerous things with your site.
Some of the symbols in Black Magic Data make changes to a concrete5 site's database or files. Incorrect use can result in unwanted changes to your database. Please use a test site for development before copying a Magic Data expression using these symbols to a live site. Please read the marketplace documentation and the symbols' built in documentation carefully before use.
Black Magic Data includes dashboard options for sandboxing to disable symbols from making changes to the database.
From version 1.9 this addon is compatible with php7. To update a site to php7 you will need to make core updates (at time of writing only on github and not released). You will also need to ensure that other addon packages are php7 compatible.
See more addons by JohntheFish.