KH2FM+ CM Shadow Stalker / Dark Thorn
Disclaimer: Kingdom Hearts 2 Final Mix + belongs to Square Enix and Disney.
An easy fight. It goes in a loop, until the second boss.
He will go into the windows, then fire a laser across the main hall, hide in the covered area.
He possesses the chandelier, and brings it down to fire out flames. When it pauses, run up and combo it. Do the RC, combo the boss.
He goes into the floor and it lights up under you. Jump to dodge. He possesses a column, stand in the center. Once they all retract, combo, do RC, combo the boss. Continue loop.
Second boss is a bit different, he is invisible until you combo him then do the RC. This is a temporary effect. I didn't have much strategy for this one.