OK hon, you went too far there, and you don't need to do anything to spawn Purpleflash. He pops on his own about every ten minutes, despawns if no one kills him, and then respawns again.
Purpleflash will pop either in the corridor between the area JUST BEFORE the Paladin well and the one to the left of that, or in that area to the left.
Bring a couple good DD around lvl 52+, another healer and yourself, and you should be fine ;) He's not a hard kill, just kind of annoying; he's a BLM, and isn't silencable, at least not by anyone I've gone with. He likes to cast -ga spells. ><
I did the exact same thing the first time I went in ^^ After going too far and dying once, I found him the second trip out.
Cheerfully trundled in as a RDM 41, smacked him with my sword, and saw I barely nicked his HP. I turned around and RLH.
Came back later and spanked him in the name of my dead RDM homies though.