the first time I fought him everytime he turned into a wolf he would aim upwards, even though i was on the ground and crouching. It totally caught me off guard the second time around when he dashed straight at me suddenly lol. Anyway what helps me is for me to walk towards the opposite end of the screen just to give me the most amount of reaction time possible, and just see which way he jumps. I think I noticed that when he aims ups, he jumps back when he transforms into a wolf. When he dashes straight at you, he'll turn into a wolf, then jump back and then at you.
His blood attacks is just like Shini said. Give yourself some walking room, and he'll try to attack you 1, 2, 3, 4 times, and then after the 4th one, just stay still and the last attack will come up around you and miss.
Later on I think about halfway through the fight, he'll throw the line of bats out at you again. You can hit those, then he'll go right into the fire pillars beneath you. During the fire pillars as long as you stay away from his arm/cape's length, you will be safe from his blood attack. You can stay outside his range or get close to him so that he extends past you and when he finishes you can whip him a few times.
When he throws out the floating red bubble, it'll go away in 3 hits, so you can either hit it right away or it's pretty easy to dodge. When the ball is out, he'll turn into bat form to scatter and come back. You can hit him now too, but watch out cuz when the bats are back in a group and you try to hit him, sometimes he will throw the whole group of bats at you. Other times he will reform himself.
During the second half when he does his fire pillars, after the second pillar he will throw that shockwave at you. Just a little heads up when he starts the pillars.
After that I think sometimes he will just come out and do a shockwave (that always caught me off guard). Just take notice whenever he comes on screen near the ground. I don't know if the animation is different for his bats and other stuff, but the shockwave I think is caused by him whipping his cape at the floor.
What I did was I picked up the holy water and all the hearts, and basically just got him down as far as I could without dying, then when he is pretty low on the health I unleashed the holy water hydro storm all up in that guy's crack. I also yelled out "yea mother

er!" as I watched him fall.