Yo guys I just found a tech you can do on the second boss, it's really fun and helpful.
So the way this works is that the Succubus's movement is stopped when you do certain attacks on her. Usually, your normal and charged shots doesn't stop her from flying, but most sub-weapons (except the sub-weapon that adds one more bullet to your shot) and your melee and most importantly, your Roll Strike, will do exactly just that.
In order to take advantage of this "feature" that I'm not even sure if it's intentional, you can do this tech I call: Succubus Corner Strike. Jump on either the top left or top right corner of her, you won't take any damage since enemies in here don't have collision damage, just a collision box that's like your normal floor or walls. After you jumped on one of the top corner, proceed to MASH THE F OUT of two buttons, down and C (your shoot button if you somehow remapped the keys). You will constantly roll, which will deal roll strike damage and stop her from flying, but you will also cancel your roll out into shoot, which you can cancel again into roll, hence the mashing. You will also not roll away from her, since you will roll straight into the corner of her collision box, which somehow helps me stay right next to her.
Doing this sequence deals awesome damage on her, with 12 attack levels I was able to drop her health to 60% by doing it once with a sub-weapon. Unfortunately this is pretty hard to do normally. The only consistent set-up I used was by quickly going to the middle of the stage, wait for her to fly from the left to the right (which she always do when you enter) and do the tech, which is the only time I can do it. Another thing to note is that this DOES NOT stop her from attacking, she'll stop flying but she'll still do the homing heart attack like normal, so you can't cheese the boss and kill her without her attacking once.
Anyways, hope you like this tech, it might help you do the second boss since she is hard as hell, much like the rest of the game. I having too much fun despite the difficulty of playing on normal on the first playthrough, lol.
