I know dex doesn't drop seraphs and as for OOO haven't gotten him to spawn yet :( I've gotten the chopper bout 50% of the time when I fight dex ... And yes I personally really enjoy the dex fight, its a lot of fun with 4 players... --- Gamertag: XRayBoosh
Neither drop seraph crystals. I haven't killed either one enough to know the reliability of their drops. I've killed Dex 3 times, never saw a Chopper. I've killed O3 once, got the twister.
Had to look a bit to find the twister, I didn't think he dropped it, but after Dex died, there it was sitting in the shallow swamp muck. --- Load the Spaceship with the rocket fuel, LOAD IT WITH THE WORDS!