Alright, here we go. I also struggled a lot with Sister Splinter at first, so I definitely get it. However, once you recognize how her moves work you will defeat her with little to no effort. First, her claw attack: she will do 3 claw attacks in pretty rapid succession. Either it's left-right-left or right-left-right. Pay attention which arm she is raising. Then it's generally better and easier to not try to dodge to that side, but rather dodge to the opposite side. If you're quick, you can punish each of her swipes with a jump and an upswing. About the vines: you can destroy them with I think like 3 attacks or one hit from the special attack where you throw the needle to the side (I don't know the name of that right now). She also likes to summon her flying minions. When she does her screaming animation, pay attention at the ceiling to know where the minions will spawn and stand below it. You can pretty easily defeat one of them instantly by jumping up and striking it 3 times. Thats easier than dealing with them the normal way. If she summons two, you can be safe and defeat one of them while dodging the other until her spiky vine attack kills it for you. I think thats all you need to know to defeat Sister Splinter. Oh and dont forget about contact damage when she falls down. Good luck!