This mod currently adds two main features with a volcanic theme.
The first of these is a new stone type called pumice which can be found deep down in the Nether. Try searching the bottoms of lava lakes to find it in patches! Pumice floats in water and rises to the top, which can be used for all sorts of interesting contraptions.
Secondly, a new weapon called the Pyroclastic Bomb can be crafted with gunpowder and Magma Blocks. This ball of molten rock explodes on contact with mobs or blocks and can be used for long-range combat.
Expect more volcano-related features in the future!