Originally Posted by gcbirzan

The script you're talking about removes this buff, which is the one that transfers threat. The damage increasing buff has a different ID and is unaffected.

Originally Posted by Ghostcrawler

We didn't explain this very well in the chat.

The answer we were trying to give was that "channels won't just get shorter and shorter the more haste you get." But a more complete answer is that hasted channels will get shorter until you get a whole additional tick, at which point the duration will go back up again. We don't want to do partial ticks or things like that because they encourage you to just recast the spell.

Originally Posted by Mewantbrains

Just tested a few things in game. I never realized it before, but it seems, IT, IIT and UH are all multiplicative rather than additive. I knew some other haste effects (druid haste talents) worked like this but I didn't realize related talents would also be multiplicative. This makes UH presence give us 22.5% haste rather than 15%. Haste from gear also stacks multiplicative with these bonuses.

So with all these multipliers (and adding in 3% haste from ret paladins/moonkins), I'm coming up with 54.5% haste raid buffed and 78% haste with UH presence (around 23.2% haste from UH). To make this more interesting, that 78% haste is multiplicative with gear. This would mean every 1% haste on gear would actually give us 1.78% haste. 20% haste on gear would yield almost 36% haste. Raid buffed with 20% haste on gear would would have around 113% haste (1.22s swing speed).

This had me very excited, but it still doesn't seem like haste beats out arp or that UH presence beats out blood. Even with haste receiving a 1.78 multiplier, arp effects a larger portion of our damage, scales, rather than being linear like haste and requires a much lower item budget for per percent increase. Even at low percentages, arp still seems to beat out haste per item point. At 0% arp and in UH presence, it takes 14 arp rating for a 1% increase as opposed to around 14.1 haste rating for 1% haste. Even being very generous with the amount of damage effected by haste and using a low % of current arp (before it starts scaling well), arp still seems to win out. At higher arp levels, due to scaling, arp wins by a more significant margin.

Being generous with UH presence, I'm still getting blood presence being better. Assuming a player haste 20% haste on gear (more than someone would have to be generous), multiplicatively with IT/IIT/3% haste buff UH presence will grant around 28% haste. Now we assume haste benefits 50% of our damage (also generous). This would mean UH presence would increase dps by 14%. Still 1% shy of the 15% damage increase from blood presence.

More than likely this is an error with the sim. Pretty sure the math above should be correct for UH, but just thinking about it, 15% damage should almost always yield more than 15% haste. Thinking about it logically, in order for UH presence to beat out blood, you would need 50% of your damage to be autoattack based with enough haste on your gear to increase the multiplier on UH presence to 30% (requires about 30% haste on gear. 756 haste rating). If the % of you damage based on autoattacks is even marginally lower, this number goes up significantly. At 45%, for example, the multiplier needs to hit 33% to increase total damage by 15%. This would require about 42% haste on your gear (1059 haste rating). Even obtaining these numbers, blood presence with arp gear should still yield higher dps.