Si tienes razon eso es debido a que una party lo mato, y para poder invocarlo debes esperar 2 horas, el cual es el delay para que la quest se borre de la instancia... lamentablemente si no esperas esas 2 horas ahi y bajas debes sacar los Charm de nuevo osea hacer toda la quest desde el principio para poder invocarlo.
Te dejo el resto de la info... me da paja traducir xD
Tips:
1) If you are stuck at one of the top floors looking for portal, this might help:
http://ratemyserver.net/index.php?page=npc_shop_warp&map=thana_step&s_ warp=thana_step
Click on the green label for the floor you are currently stuck in, it will show you the floor map and also a green label to thana_step (that is the portal you should go to get out of that floor).
2) If you are getting the message “The statue is emanating an intense light, making it so hot” at the statues or “You cannot approach the crest because it is generating intense heat.” at the top floor, that means Thanatos have been summoned not long ago. You have to way at least 2 hours for the quest to reset.
3) If you have finished the quest and you want to summon the Thanatos Phantom you need to get the five Charm Stones again, so you need to start again the entire quest (but you don’t need to talk to Ditze). Remember to wait 2 hours since you defeat the MVP.
4) If you don’t find the warp to the next floor in the un-mapped floors (from 9th to 12th) just look here, the warps you’re looking for can be marked.
http://ratemyserver.net/index.php?page=areainfo&area=1013