Doesn't seem to summon at all. I killed it a few times today and it didn't summon me once even when I tested pulling from one side of the portal to the other. And yes I did damage it down first.
Just got jumped by the Fabled Azureake. Thought I would add that the Fabled Frosty Breath 2 did 4800 damage to a 72 Necro with resists in the mid 200s to low 300s. If I would have known how much damage it did, I would have played it a little differently. Good luck.
For fun, I took a lvl 68+ group to CS early morning Mar 3, 2006. Mercilessly and with extreme prejudice we slaughtered every Drake, Wyvern and Othmir. In a 3hr span of time we popped 2 Fabled Yvolcarns and 2 REGULAR non-fabled Azureakes.
Can anyone confirm that the FABLED Azureake is actually spawning in game?