Hey, being trying to contribute more recently, and here's something I discovered during my guild's malygos attempts this week.
As a melee class if you run directly northwest during the transition between dps and vortex phases, when you get thrown up in the air you should be able to attack malygos. I tested this every chance I got (Which was a lot while we were working on 6 minute maly) and it worked every time. It seems though, gathered from other results, there is a bit of a sweet spot between the middle of the circle, and the northwest sector where you want to stand, facing northwest. If you go to far northwest, say to the very edge, it will not work.
Another way which is probably more well known is having warlocks use Demonic Circle: Teleport.
Hope some of you find this useful =)
Edit: Courtesy of Kongmarius - Rogue's killing spree works aswell for dropping down during vortex.
Edit: Unfortunately I'll have to wait for a week to get a screenshot, what it would basically be is my action bars lit up while in the air, but here is a mini-map ss of where to run -(I had to make the image bigger to get it to be a proper thumbnail, hence the black box.