is there a certain level or area where everyone is getting this? can i use the combat arena and just have a bunch of soldiers respawning forever? 
 
n e help would be appreciated 
 
EDIT: seems no u cant use the combat arena since i managed to get a 2000 hit combo and no trophy. i've played thru the game twice now and the most ive gotten is about 250 and the only reason it wasn't more is because everyone was dead

Hercules is probable a good place or when you meet the centaur when you enter tartarus 

i got it. i just ended up cheating it with the Hades Claws. just find a good spot with a lot of foot soldiers and a wall, keep the claws level 1 and just keep ripping souls out of the enemies. it does no damage to them and u can even get hit a bunch of times without it breaking the combo. took about 2-3 minutes

Also the room with the infinite respawning dogs right after you kill 

Last section of game was when I got it. I managed to loop a sequence and get it. 
 

I got it in the area immediately after getting the Claws of Hades.  Once you swim up into the room and it tells you to use the souls of hades or whatever.  There are a lot of soldiers that spawn.  Use the L1+O soul grab move and just spam it till you hit 1000, I had a 1100 hit combo by the time the last guys died, and that is with accidentally grabbing a couple enemies and smashing them.

I did it on the scorpion boss, which is quite easy to be honest, all you have to do is to rush behind one of him "damage-able" legs and start hammering it (the scorpion will be stunned and he wont summon little scorpions - only if done right ofc)