Spark

Well there's no real way to speed up your reaction time, and it doesn't really matter as the over heads in BB aren't super fast you just have to condition yourself to respond to them correctly without having to think about it. Like if you see Ragna do dead spike, you shouldn't even have to think about what to do and just walk forward and 6D it immediately. There's no real easy way to practice this besides playing a lot. Also having someone who is improving along with you is the fastest way to get better. Since a lot of players in out scene started playing BB at the same time no one was super far ahead, so no one was just destroying everyone. So when someone got better it was easy to catch up and it would just go back and forth.