A single cleaving Nether Tempest hits for about 85% of the damage of a full stack of Warlock DoTs.
NT Avg Hit: 3469 http://i.imgur.com/C72nwAF.png
NT Avg Cleave Hit: 1819 http://i.imgur.com/u8TgZ0P.png
Corruption: 3431 http://i.imgur.com/85x1Tgd.png
Agony: 4119 http://i.imgur.com/r2dpHpS.png
UA: 5439 http://i.imgur.com/1PymEr7.png
Average total NT DPS: 3469+1819 = 5288
Average Warlock DoT DPS: (3431+4119+5439)/2 = 6494
Add in ~5% more crit for the Mage, and we're at 5552 Nether Tempest DPS vs 6494 Warlock DoT DPS.
That's 85% of a full DoT stack on a single spell which always only takes one global to apply, procs ~70k instant nukes, and is not even really a Mage's main form of attacking. I would say the situation is pretty ridiculous right now... Note that these numbers are from an RBG where I was able to spend more than my regular armount of shards under a spellpower increasing effect, which means in an arena the numbers would be even more favorable to Nether Tempest.
Edited by Nadagast, 14 March 2013 - 03:14 AM.