Rose Thorns Storm is an attack used by Crona, Ragnarok, and presumably the Black Clown by making use of the Black Blood. The move first requires Crona to manifest a large number of vine-like tentacles from their body. The tentacles then rise towards the sky, forming what appear to be black rose blossoms at their ends. The force with which Crona raises their tentacles in the air creates a powerful shockwave before finally landing on their opponents with incredible force, crushing them on the ground or blowing them away with the fierce wind.
Due to the mass of the tentacles themselves, plus the sharp thorns that seem to sprout out all around their serface, this attack is highly dangerous and, although it has only been seen used for close combat, it can be considered to be much more effective for large range attacks. Also, the attack seems to have a side-effect to meisters who are successfully hit by the tentacles' thorns. Just like real life, thorns often contain poison, and these thorns seem to cause weapons and meisters to lose sync with each other, demonstrated by how both Black☆Star and Maka had their hands burned when they touched their respective weapons after that very attack. Only the family "bond" between Spirit and Maka was able to counter this after-effect.