If it is world pvp, it is probably the Gaze of Aman'thul you get for some raid quest in NH. Alternatively it could be a Failure detection Pylon, the former is just way more likely.
If it was an arena it could also have been shaman totem (Summons a totem at the target location for 30 sec. All allies within 20 yards of the totem gain 10% increased health. If an ally dies, the totem will be consumed to allow them to Reincarnate with 20% health and mana). I don't pvp that much but I think I have seen that work once.
There's Darkmoon Card: Twisting Nether that has a small chance of reviving you. I used to use it on my Hunter back in BC and WotLK world PvP, got lots of whispers from people thinking I rused them with feign death. I miss the game being fun...