I've just started exploring the use of two archons instead of the usual one, by giving them both shadowfields. In the first game I was running a freak show list, and used the excuse of wanting my harly troupe to be escorted with both the armour of misery and the archangel of pain. While I was at it, I threw in a shadowfield for my second archon too.
In the first game (against tau), with some clever positioning that archon took only one wound after a full round of tau shooting. Granted, he had to break the raider first, but my opponent and I were both astounded that those harlequins were allowed to live another turn
In the latest game against Blood Angels, I ran pure DE, but still stuck a second archon with my warlord into a six man unit of incubi. I deploy and maneuvre around so that I keep in range of his mephiston with assault termies with storm shields and thunder hammer, should they come out of their land raider. I knew that incubi are ruthless, but I was honestly a little anxious to charge. But when I did, the second archon meant I could take mephistons challenge without risking my warlord. He lived to see the second round of combat, where he died with the very last save to the st10 monster. By then there were no termies left, and mephiston was promptly dispatched by the untouched incubi.
From what I can tell a lot of people here don't like the Archon be cause he is so expensive, but I don't think there is a tougher meatshield in the game (2++ is exclusive to DE, I think?). This means any risky maneuvre you may be thinking of involving your warlord and some glass hammer unit (harlies, incubi) is virtually safe. I have not had to deal with a scenario yet where my warlord archon had to make a 2++ to save his life, even though I was counting on it.
Please give me your thoughts on the matter. I feel like this strategy solves some issues with some of our units being too difficult to get into combat safely, especially when deep striking that unit in the middle of a gunline.