Skin changes – Rammus made of lava and fire.. Specific in-game changes:

• Model: New textures for Rammus..
• New particles: New textures for Rammus and Powerball..
• New animations: New particles for Powerball..

Skin bio & introduction: – An unstoppable warbeast drummed up from the Infernal hordes, Rammus simply chooses a direction and begins spinning through homes, armies, and nations alike, burning everything to ashes.

How to get this skin? – The skin is not available for purchase and has been placed in the Legacy Vault (they can still be mystery gifted, and only appear in a champion’s information tab if owned). The vault is usually opened for limited runs and this skin can then be purchased in the Riot Store. In my experience it can be rather long between each opening of the Legacy Vault, hang tight!

Worth buying? – Molten Rammus is a Legacy vault skin — rarely available and not in the regular store. It includes custom particles, new animations. You can preview any skin for free on the PBE server before buying. Learn how to access the PBE here.