High pings do put you at a massive disadvantage, if you are on a mage class I recommend you watch Mr Happy's video on Titan, learn his ability rotation off by heart, and sprint when you know Weight of the Land is up next, this is the ability which affects high pings worst. I have been able to consistently avoid on a 280ms ping using this method, but for a class which requires it's tp, clearing this fight is unrealistic for players with this kind of latency. The problem is all testing is done in house, extremely close to the servers, those are the conditions the fight is balanced for.

Also, SE have accepted this as a problem (and not the one that Cyril is mentioning, they admitted EU pings to be an issue 2 days ago), its in their accepted bugs forum, so hopefully some kind of lag compensation is on the way.