Imperious Task Force/Strategy
In both, however, whenever Romulus resurrects himself by sacrificing one of the Nictus essences, his version of Stygian Return works as a large PBAoE form of Howling Twilight, and stuns everyone within range, even through some Tanker mez shields. It is quite common for the whole team to flee upon Romulus' defeat in order to break line of sight with his body to avoid this effect.
One strategy is to have a Tanker/Scrapper/Brute focus on the healing Nictus essence while the rest of the team draw Romulus and the other Nictus essence away. Without the healing Nictus essence they are much more vulnerable. The Tanker and Brute will have their own versions of Gauntlet to aid in pulling the healing Nictus essence away, while the Scrapper will have to either have Taunt, or intecept the Nictus essence while the rest of the team is drawing Romulus' attention, and damage it enough to raise their own threat value higher so that the healing Nictus essence locks onto them.
An important note to consider is that the Nictus essences have an invisible tether to Romulus, and cannot be pulled too far a distance before ignoring all taunts and threat values and rushing back to Romulus.
A second note is that the healing Nictus essence must be within Romulus' line of sight when he is defeated, otherwise he will not use it to resurrect himself. The worse comes to the worse when Romulus is defeated, and the only enemy left is the healing Nictus essence...
The basic method of pulling involves someone (generally the player who will be tanking Romulus) attack Romulus with a range attack to pull him away from the Nictus essences. From there, the enemies will be separated enough for the second player to intercept the Nictus essences. If there is a player with Healing or Regeneration or Resistance and Defense buff powers to aid the second player, they might choose to aggro all of the Nictus essences together (this would solve the problem of telling which Nictus essence is which) while the rest of the team focuses on defeating Romulus before the second player either loses aggro, or is defeated.
The second strategy is much more simplistic in nature - damage Rom so much and so fast that the healing Nictus simply cannot keep up with the damage. This usually involves a balanced high damage team as well as lots of -regen/-resistance. One simple method of raising the team's damage to a extremely high degree is to have some members of the team carry Biological Mutagens, and use them one at a time, as each usage lasts for five minutes. If that is not enough, then Chemical Burn would come in use to further increase the damage Romulus takes from the team.