General tips!(im playing on apoc diff btw)
If you can try and enter Every boss fight with full chaos get them down change form then pound away so far every boss fight ive done using this has been over very quickly guessing this wont work on some of the later/endgame bosses but for the stuff ive killed so farstart its worked a dream.
worked best on greaver first smash the crystal in its chest when you knock him her it down the first time go throught the methods to knock it down the 2nd time run up close change to chaos and beat away boss should die well before your form changes back
for tiamat i found keeping close when on the ground phase the best method when she rears up to do her fireball spam dodge/run and get behind her she will ALWAY stop the fireball move and fly up to ground bomb dodge away to avoid the shockwave and move back in and repeat to deal the pain the Ripsaw? sword attack is the king always attack her head! no other body part seems to take damage run in jump rip saw dodge out watch for fireballs etc repeat a few times and shes toast took me 5mins to killer doing this method phase 1 is the hardet part of this fight
Hope this helps some