My strategy for the first two phases is to stay in front, locked on to the head and just dodge most attacks left. When she does the attacks where she leaves her arms on the ground while recovering, I go in for two R1 hits. This works perfectly, I usually get to phase 3 without taking any damage.
My strategy for phase 3 is to fail and die. Her forward extended attacks have so much range I can't get to the arms quickly enough to get in hits (especially since you have to get her actual arms, not the ones she's holding). If I try staying closer while dodging, she will connect eventually which means death. If I try to get to her back leg to attack the one available arm, this triggers the jump fairly often. Most of the time, staying perfectly still means the jump doesn't hit you, but every so often, it will hit and it's another one-hit death for me. Considering how long it takes to get her down with her absurd HP and my pathetic damage, one of these one-hit-kill deaths will inevitably happen, ruining a good 5-10 minutes of work in a split second.
I just don't like this fight, it's difficult for all the wrong reasons. I took nearly 50 tries on Orphan of Kos but while I hated his guts, I respected that fight. It was tough but fair. I even respected the defiled Watchdog fight, as even though his charge is one-hit-kill, it can be dodged 100% of the time. Defiled Amygdala with her jump just feels random. If she decides she's had enough, she will randomly connect with her jump and that's game over, leaving you wondering what you could've done better. It's the only fight in the entire game I would call cheap.
I did a flawless first half without getting hit once and still ended up scrambling near death with just a single blood vial left. I had to become agressive to end it quickly and just about pulled it off. Feeling pretty much invincible right now, that'll end soon enough when I go after Laurence though. 